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Diamond Glossary - All
This is our diamond glossary of terms used in the diamond jewelry business....
facts about diamonds-
Click a letter to view terms -
Diamond Glossary - AAbrasion: Tiny nicks along facet edges, usually caused by contact with other diamonds. Producing white fuzzy lines instead of sharp crisp facet edges.
Abraded Culet: A culet that has minor abrasions on it.
Age: The age of a diamond ranges between 1 billion to 3.3 billion years.
Alloy: Combination of 2 or more metals.
Alluvial Diamond: A diamond that has been transported by water and deposited in seas, lakes or streambeds.
American Cut: Proportions and facet angles of a diamond that were mathematically calculated by Marcel Tolkowsky to produce maximum brilliancy consistent with a high degree of fire in a round brilliant cut diamond and are considered by many to constitute the "Ideal Cut" diamond. These figures, computed as a percentage of the girdle diameter, are as follows: total depth of 59.3% (without provision for girdle thickness); crown height of 16.2% (table 53% and Crown angle of 34.5 degrees); pavilion depth of 43.1% (pavilion angle of 40.5 degrees).
American Gem Society (AGS): The American Gem Society was established in 1934 by a select group of independent jewelers and Robert M. Shipley, founder of the prestigious school of gemology, the Gemological Institute of America (GIA). It was their vision to create an association dedicated to setting and maintaining the highest possible standards of business ethics and professionalism in the jewelry industry. Today, American Gem Society members continue their dedication to ethics, knowledge and consumer protection.
American Gem Society Laboratory (AGSL): Since 1996, the AGS Laboratories is the world's premier diamond grading laboratory and the only diamond grading laboratory backed by the jewelry industry's premier consumer protection agency, the American Gem Society, and the first prominent diamond grading laboratory to offer diamond grading reports with a Diamond Cut Grade for the round brilliant cut diamonds, princess cut, oval brilliant, and emerald cut diamonds.
American Gem Trade Association (AGTA): the American Gem Trade Association and its members are active in all areas, from mines and research labs to wholesale offices, design studios and retail showrooms. As a result, the AGTA is recognized as the voice of the natural colored gemstone and cultured pearl industries. Some of the most significant contributions to the trade have been the creation of the AGTA Code of Ethics and Principles of Fair Business Practices, the Gemstone Enhancement Manual (G.E.M.), along with the opening of the AGTA Gemological Testing Center in New York in October 1998.
Anneal: A treatment process of heating and slow cooling of colored gemstones, color enhanced diamonds, and metals.
Appraisal: A written estimate of the value of the item described. They can be used for insurance purposes and should be updated every few years.
Arkansas Diamond: An Arkansas diamond is actually a rock Quartz crystal.
Art Deco: Art Deco was a style popular from the mid-1910's until the late-1920's. This style originated in Paris, France. Geometric lines and angles, with very few curves, characterize Art Deco pieces. The Asscher Cut diamond and the Emerald Cut diamond were developed and became popular during this period.
Asscher Cut Diamond: A square step cut diamond named after its inventor, Joseph Asscher.
Asscher, Joseph: Joseph Asscher was an eminent diamond cutter who cut the 3,106 carat Cullinan diamond. Asscher worked in Amsterdam. In 1902, his company, the Asscher Diamond Co., developed and patented the Asscher cut, a squarish step cut with an almost octagonal outline. This new cut enhanced the fire and light of the stone; it had a small table, a high crown, wide step facets, a deep pavilion and square culet. This cut became very popular in Art Deco jewelry and was a forerunner of the Emerald Cut diamond.
Average Girdle Diameter: The average measurement of the minimum and maximum diameter of a Round Brilliant Cut diamond.
Diamond Glossary - BBaguette: A French word meaning rod or stick. A style of step cutting for small, rectangular or trapeze-shaped gemstones, principally diamonds used as accent or side stones.
Bar Setting: A diamond setting style that holds each diamond in by a thin bar, shared between the two diamonds.
Barion Cut Diamond: This has a traditional step-cut crown and a modified brilliant-cut pavilion. This is referred to as a mixed cutting style. A square Barion Cut diamond has 61 facets, excluding the culet.
Baroque: Irregular in shape, such as baroque pearls, tumble-polished stones, or freeform shaped gem materials.
Bearded Girdle: Tiny, numerous, hairlike fractures extending into the diamond. The outermost portion of the diamond, called the girdle, can develop small cracks that resemble whiskers during the shaping process. If a diamond is rounded up too quickly in the shaping process, the surface of the girdle will lack the smoothness and waxy luster of a finely turned girdle. The bearding can sometimes be removed, if not too dramatic, with slight re-polishing, and if the finished weight allows it.
Bezel Facet: On a Round Brilliant Cut diamond, these are eight large kite-shaped facets on the crown, the upper points of which touch the table and the lower points, touch the girdle. Also called top main facet. Some diamond cutters further distinguish four of these as "quoin" or "top-corner" facets.
Bezel Setting: A rim that holds the diamond and completely surrounds the diamond along the area just above the girdle. Bezels can have straight edges, scalloped edges, or can be molded into any shape to accommodate the diamond.
Birthstones: Birthstones have their roots in ancient astrology, and there have been many birthstone lists used over the years. The most common one today is based on a list first publicized by the U.S. jewelry industry in the 1950s. This list assign birthstones as follows-
Black Diamond: When a diamond is dark gray, a very dark green, or truly black, it is referred to in the trade as a "black diamond". Such a stone may be opaque to nearly semi-transparent.
Blemish: Any surface imperfection on the surface of a diamond, such as a nick, knot, scratch, abrasion, minor crack or fissure (cavity), or a poor polish. Also, a natural or an extra facet, visible on or through the crown, usually is considered a blemish.
Blue Diamond: A diamond with a distinctly blue body color, even if it is very light in tone, is a fancy blue diamond. Boron that is present in the crystal structure is responsible for this color. A blue color may also be induced artificially and is referred to as a color enhanced diamond.
Blue White: This is a term that I haven't heard in many years... actually it was probably last century! It was still commonly used up till the mid 60's. Federal Trade Commission rulings state that is it an unfair trade practice to apply the term to any diamond having a body color other than blue or bluish. An American Gem Society ruling prohibits the use of the term by its members. Flagrant misuse of this term has made it meaningless and it is no longer used.
Blueground: A miner's name for "kimberlite", the rock that contains diamonds in the South African pipe mines.
Body Color: The color of an unmounted diamond as observed when examined under a diffused light against a hueless (colorless) background free from surrounding reflections. The diffused light eliminates glaring reflections and dispersion, which would otherwise confuse the color determination.
Bombarded Diamond: A diamond that has been subjected to a stream of fast electrons, neutrons, deuterons, etc. The purpose of bombardment is to alter the color of a diamond.
Bort: Industrial grade diamonds.
Bow Tie Effect: An effect caused by a shadowy area visible in some fancy shapes, caused by light leaking out the bottom of the diamond. A large bow-tie in the center of a fancy shaped diamond detracts from beauty and lowers the value. (also 'Butterfly')
Brilliance: The total amount of white light returned to the eye from a diamond or colored stone as the result of internal and external reflections. The major factors that affect the amount of brilliancy in a gem are refractive index, proportions, polish and transparency.
Brilliant Cut: One of three styles of faceting arrangements. In this type of arrangement, all facets appear to radiate out from the center of the diamond toward its outer edges. It is called a brilliant cut because it is designed to maximize brilliance. Round, oval, radiant, princess, heart, marquise, and pear shape diamonds all fall within this category of faceting style.
Brillianteering: The placing and polishing of the 40 remaining facets on a single cut diamond after the 8 main bezel, 8 pavilion main, and the table have been placed and polished. By adding the additional it is now called a "full cut" diamond.
Brown Diamond: Although not as frequently encountered as a yellow body color, brown tints in diamonds are next to yellow in occurrence.
Bruise: Inclusions consisting of surface crumbling, often accompanied by tiny, root-like feathers .
Bubble: Any transparent inclusion in a diamond; e.g., a tiny diamond crystal or a grain of a different mineral. It will look like a bubble.
Burned Facet: This facet may appear whitish, or burnt, as a result of the cutter polishing the facet "against the grain". The excessive heat of polishing will make the diamond red hot and the surface will actually start to burn. This can also happened if the diamond is not properly protected from exposure to the atmosphere while being heating during repair work. A burnt facet can be re-polished.
Butterfly: Term used to describe the dark area located across a table, sometimes found in fancy shapes (see 'Bow Tie').
Diamond Glossary - CCanary Diamond: Fancy color diamonds with an intense yellow hue similar to that of a canary bird. The yellow may be very slightly greenish or slightly orangey.
Cape: An outdated diamond color term referring to diamonds with a yellowish body color. This term originally referred to the Cape of Good Hope, referring to South Africa. The body color of diamonds produced by the South African mines was distinctly more yellow than the average diamond body color of Brazilian diamonds. This term is almost never used anymore because it is very inaccurate.
Carat Weight: The measurement unit for the weight of gemstones. The origin of the word carat is from the seeds of the carob bean that were used to balance scales in ancient times. In the early 1900s the metric carat was standardized as one carat equaling 200 milligrams. When you buy a diamond the weight of a diamond is measured out to the hundredth of a carat (2 places to the right of the decimal point). It is expressed as "ct." or "Ct.", for example 1.23ct.
One carat can also be divided into 100 "points", just like one dollar has 100 cents. A 0.75 carat diamond is the same as a 75 pointer, a 75 point diamond, or 3/4-carat diamond. The weights of all the diamonds in a piece of jewelry can be added up to arrive at a "total carat weight" of the diamonds... this is can expressed as "ct.t.w." or "ctw.", as in 0.85ct.t.w. or 0.95ctw.
This should not to be confused with the term "karat", which refers the purity of gold.
Carbon or Carbon Spots: This is a term used by some people in the jewelry industry to describe the appearance of certain diamond inclusions that appear black... typically a dark included crystal. Diamonds are 99.95% pure carbon; but 25 other different mineral inclusions or small crystals, have been found within diamond as well. These are not carbon spots, but rather small crystals that were trapped within the host diamond as it was forming in nature. Sometimes, they just happen to be dark in color. The most common mineral found within diamond is diamond.
Cavity: An inclusion consisting of a large or deep opening in the diamond.
Center Stone: The main stone in a piece of jewelry with multiple stones. This stone is usually the largest and most prominent.
Certificate or "Cert": Another term for a Diamond Grading Report. A document produced by a disinterested 3rd party (typically a Gemological laboratory) that describes a diamond's characteristics. This report should only list the characteristics of the diamond and not refer to any prices.
Certified Gemologist: A title awarded by the American Gem Society to qualified members. To qualify, a person must study colored stones and their identification, along with diamond grading and appraising. Also they must prove proficiency with several written examinations and a diamond-grading examination.
Champagne Diamond: A diamond that has a color similar to... you guessed it, champagne!
Channel Setting: Diamonds set into a row where the diamonds are held into place by grooves cut into a strip of metal along the edge of the piece of jewelry. Used quite often for wedding and anniversary bands.
Chip: A chip is a shallow opening on the surface that is the result of damage that occurs after cutting.
Clarity, Diamond Clarity: Diamonds have internal features, called inclusions, and surface irregularities, called blemishes. Together, they're called clarity characteristics. A diamond clarity grade is determined by the relative absence of clarity characteristics. The Diamond Clarity Grading System was developed by GIA (Gemological Institute of America) in 1953 and is now the common international language when we talk about diamond clarity. The 11 diamond clarity grades are as follows-
Flawless (FL): no blemishes or inclusions when examined by a skilled grader under 10X magnification.
Internally Flawless (IF): no inclusions when examined by a skilled grader, and only insignificant blemishes under 10X.
Very Very Slightly Included (VVS1 and VVS2): contain minute inclusions that are difficult for even a skilled grader to locate under 10X. VVS1: extremely difficult to see, visible only from the pavilion or small and shallow enough to be removed by minor repolishing. VVS2: very difficult to see.
Very Slightly Included (VS1 and VS2): contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) for a trained grader to see under 10X.
Slightly Included (SI1 and SI2): contain noticeable inclusions which are easy (SI1) or very easy (SI2) to see under 10X. In some SIs, inclusions can be seen with the unaided eye.
Included (I1, I2, I3): contain inclusions which are obvious to a trained grader under 10X, can often be easily seen face-up with the unaided eye, seriously affect the stone's potential durability, or are so numerous they affect transparency and brilliance.
Clarity Enhancement: Any process used to improve the apparent clarity of a diamond. This is a relatively complex subject... please refer to the following page on the subject- Clarity Enhanced Diamonds.
Clean: A trade term to refer to a diamond that relatively free of any inclusions... typically a grade of SI1 or higher. It is not a standardized term, so one person's clean diamond is another person's not clean diamond. It is a term that is prohibited by the American Gem Society for use by its members. It is also prohibited by the Federal Trade Commission, unless the diamond meets the FTC′s definition of the term perfect. There is another term "Commercially Clean" which would be a grade lower than "Clean", about SI2 to I1.... again, this is not a standardized term.
Cleavage: The property of some crystalline minerals, such as diamond, to split along certain planes when struck by a blow. These cleavage planes result in a clean flat surface that looks very much like they are a polished facet.
Cleavage Crack: A break parallel to a cleavage plane. It is characterized by a two-dimensional nature; intersections with facets are usually straight lines. It is generally the most dangerous characteristic in a diamond, if it is present, since it could affect the durability as well as the diamond's beauty.
Closed Culet: A culet, the small facet on the bottom of a diamond, that is too small to be resolved with the unaided eye and that can be seen only with difficulty under 10x magnification.
Closed Table: A trade term used to designate a small table diameter. However, its interpretation and use varies. It may refer to a diameter less than the American cut 53% (of the girdle diameter) or, more frequently, to a table smaller than about 60%, because so many of the stones cut today have tables well over that 60% figure.
Cloud: A group of extremely tiny inclusions that are too small to be distinguishable from one another, even under high magnification. The result is that, under a microscope, this grouping often looks like a soft transparent cloud inside the diamond. Wow.... a cloud inside of your diamond!, cool!!!
Cluster Setting: A type of diamond setting with many diamonds in a single group.
Coated Diamond: A diamond with a surface coating which masks the true body-color. The coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.
Color Grading: Determining the body color of an unmounted (loose) diamond when compared to the known colors of a "master set" of diamonds. This needs to be done under a controlled lightning environment by someone who is trained in the grading system.
Color Origin: A determination of the cause of color in Natural Fancy Color Diamonds. Diamonds that are naturally colored are very rare and expensive. Fancy Diamonds are also available as Color Enhanced Diamonds, where the color has been induced by artifical means. A Gemological Laboritory is able to determine the cause of the color in a Fancy Color Diamond.
Colored Stone: All natural gemstones other than diamonds.
Critical Angle: The largest angle measured from the normal at which light can escape from and optically dense substance, and the smallest angle to the normal at which light is totally reflected within the dense substance. Pretty simple, huh!
Crown: The upper portion of a faceted diamond, which lies above the girdle.
Crown angle: The angle of a diamond's bezel facets (or, on emerald cut diamonds, the row of concentric facets) as measured from the girdle plane. This gentle slope of the facets that surround the table is what helps to create the dispersion, or fire, in a diamond. White light coming up from the pavilion exits the diamond in the crown area... exiting at different angles which breaks up the white light into its spectral colors, creating a beautiful play of color inside the diamond.
Crown Height: The height of the diamond that is above the girdle. Measuring from the girdle to the table facet.
Crown Height Percentage: The crown height expressed as a percentage of the average girdle diameter of a Round Brilliant Cut diamond or the width of a Fancy Cut diamond.
Cubic System: A crystallographic system, the crystals of which may be described by reference to their axes of equal length, each situated perpendicularly to the plane of the other two. Diamond belongs to this system. Another bit of useful information!
Culet: An eight sided facet on the bottom of a diamond. This facet may or may not be present... its purpose is to protect the tip of the pavilion from being chipped or damaged. If it is present, it is he smallest and the 58th. facet of a full-cut diamond. The grades of the culet are- None, Very Small, Small, Medium, Slightly Large, Large, Very Large, and Extremely Large.
Cushion Cut Diamond: A square or rectangular shaped brilliant cut diamond with rounded corners. The overall shape is similar to a pillow or cushion. It is a modern version of an Old Mine Cut diamond.
Cut: Cut refers to the angles, symmetry, and proportions a diamond cutter uses in transforming a rough diamond into a polished diamond. One of the 4Cs used to evaluate a diamond, see Diamond Cut
Cutting Style or Faceting Style: this refers to the shape, size, and arrangement of the facets on a diamond. It can be categorized into the following three basic types:
and Mixed Cut.
CZ (Synthetic Cubic Zirconia): A widely used diamond simulant. See Diamond Simulants.
Diamond Glossary - DD: The highest color grade on GIA's Color Grading scale... at the beginning of the "Colorless" category.
Dark Center: A dark area visible through the table in a stone with an inferior cut... the diamond is too deep.
Dark Included Crystal: An inclusion in a diamond which is dark in color. Many times, it is incorrectly referred to as a "carbon spot".
De Beers: De Beers and the various companies within the De Beers Family of Companies engage in exploration for diamonds, diamond mining, diamond trading and industrial diamond manufacture. De Beers is active in every category of industrial diamond mining: open-pit, underground, large-scale alluvial, coastal and deep sea. Mining takes place in Botswana, Namibia, South Africa and Canada.
Dead Stone: A diamond so heavily included or so poorly cut that there is no brilliance (life).
Deep Cut: Refers to the angles, symmetry, and proportions a diamond cutter uses in transforming a rough diamond into a faceted diamond. When a diamond is cut too deep, it will leak light through the side or bottom. This results in a diamond that is dark.
Depth: The height of a diamond from the culet to the table. The depth is measured in millimeters.
Depth Percentage: On a diamond grading report, you will see two different measurements of the diamond's depth- the actual depth in millimeters and the depth percentage (a percentage in relation to the diameter of a diamond). The (total) depth percentage of a diamond is the sum of the crown height, the girdle thickness, and the pavilion depth. It can give an indication of quality of the cut of the diamond.
Dodecahedron: One of the seven basic forms in the highest symmetry ("hexoctahedral") class of the cubic, or isometric, crystal system. It has 12 rhomb-shaped faces, each of which intersects two of the crystallographic axes and is parallel to the third. This form is uncommon in gem diamonds. Did you understand that?
Diameter: The width of a round diamond... used as the reference point for the diamond's proportions.
Diamond: A form of crystalline carbon, made up of 99.95% pure carbon atoms arranged in an isometric, or cubic, crystal arrangement, singly refractive, a refractive index of 2.417, a dispersion index of 0.44, and a specific gravity of 3.52. It is by far the hardest of all known natural substances (10 on Mohs scale); only manmade Borazon and synthetic diamond are as hard. Now, that is a really romantic description of a diamond!
Diamond Cutting: The process by which a rough diamond is transformed into a finished, faceted stone. As a first step, cleaving, sawing, or lasering is used to divide the rough into smaller, more workable pieces that will each eventually become an individual polished stone. Next, bruting grinds away the edges, providing the outline shape (for example, heart, oval or round) of the diamond. Faceting is next done in two steps:
> during blocking, the table, culet, bezel and pavilion main facets are cut (making it a single cut diamond)
> next, the star, upper girdle and lower girdle facets are added (now it is called a full cut diamond).
Once the fully faceted diamond has been inspected and improved, it is boiled in hydrochloric and sulfuric acids to remove dust and oil.
Diamond Cut: A name sometimes used in the colored stone gem trade for colored stones that are cut like a brilliant cut diamond.
Diamond Cutter: A person engaged in the cutting and polishing of diamonds.
Diamond Gauge: An instrument that is used to measure a diamond's length, width and depth in millimeters.
Diamond Grading Report: An expert opinion of the quality of a diamond, that contains information on identification, enhancements, carat weight, shape outline, measurements, color, clarity, and cut. Many include diagrams, top and bottom plotting diagrams of the diamond's clarity characteristics. Usually issued by a disinterested 3rd.party, typically an independent gemological laboratory.
Diamond Saw: A saw used for sawing through diamonds as part of the diamond cutting process.
Diamond Syndicate: In the early days of South African diamond fields, the word "syndicate" was used to refer to various groups of individuals and companies that held controlling interests in diamond production and distribution. In 1890, a syndicate consisting of ten firms offered to produce all of De Beers Company's diamonds. The term syndicate is no longer meaningful, it is often applied to De Beers Group, because it holds a controlling interesting in a number of diamond-mining companies and in companies that have buying contract with independent producers, including the Diamond Corporation, Ltd.
Diamond Trading Co., Ltd.: The organization that markets to the diamond industry the gem diamond it buys from the Diamond Purchasing and Trading Co., Ltd.
Dispersion: The spreading of white light into its spectral colors. This typically occurs in the crown area of a diamond. Also referred to as fire.
Doublet: A form of gemstone trickery that was devised to allow inexpensive materials to imitate the more valuable gemstones before modern synthetics were available. A doublet can take several forms but always involves a fake gemstone produced by gluing together two different materials to form an illusion.
Durability: A combination of hardness, toughness and stability that describes a specific gemstone's ability to resist wear. The durability of a gem depends both on its hardness and "toughness". It may be quite tough but easily scratched, or it may be exceedingly hard but lack toughness because of easy cleavage. Diamond is highest on the scale of hardness and, despite it rather easily developed octahedral cleavage, it is among the toughest of gemstones.
Diamond Glossary - EE: A grade in GIA's Color Grading System.... in the middle of the "Colorless" category.
EGL: European Gemological Laboratory, EGL has franchises in a number of cities around the world which grade diamonds and offer other gemological services. EGL USA Group has laboratories in New York City, Los Angeles, Vancouver, and Toronto. EGL USA is not affiliated with any other EGL labs outside North America. Every certificate issued by an EGL USA lab states "A member of the EGL USA Group". Certificate numbers are preceded by either "US" or "CA" to indicate country of origin and to provide consumers the assurance that their certificate has been issued by a member of the EGL USA Group. Please be careful of diamond grading reports issued by other EGL labs... they have been known to somewhat inaccurate!
Emerald Cut Diamond: A rectangular-shaped diamond with cut corners. On the crown, there are three concentric rows of facets arranged around the table and, on the pavilion, there are three concentric rows arranged around the culet. This type of cut is also known as a Step Cut because its broad, flat planes resemble stair steps.
Enhancements: An artificial process used to improve the apparent beauty of a gemstone. Common enhancement processes include heating and fracture filling.
Excellent Cut: A GIA and HRD-CGL grade for the highest cut and polish of diamonds.
External Characteristics: Irregularities located on the surface of a diamond.
Extra Facet: Small facets added to remove clarity characteristics or correct minor cutting discrepancies. Any facet added to the stone which is in excess of the facets normally required to complete the polishing. Usually found along the girdle to remove any imperfections.
Eye Clean: A trade term used to describe a diamond with inclusions or blemishes that can be seen with the unaided eye. It is prohibited by the American Gem Society for use by its members. It is also prohibited by the Federal Trade Commission, unless the stone meets the Commission′s definition of the term perfect. I've heard it more used in the colored stone trade than the diamond trade.
Diamond Glossary - FF: A grade in GIA's Color Grading System.... at the end of the "Colorless" category.
Face Up Position: When you view the top of a diamond, perpendicular to the table.
Facet: The smooth, flat faces that are polished on the surface of a diamond. They allow light to both enter a diamond and reflect off its surface at different angle. The way light interacts with these facets affects a diamond's brilliance and sparkle. A Round Brilliant Cut diamond has 58 facets (or 57 if there is no culet). The shape, quantity, and arrangement of these facets will differ slightly among other fancy shapes.
Faceted Girdle: Sometimes diamond cutters will place facets on the girdle to eliminate noticeable breading, roughness, or to help camouflage a thick girdle.
Fancy Diamond or Fancy Color Diamond: Any diamond with a natural body color strong enough to be attractive, rather than "off color". A body color of light yellow or light brown would need to be beyond the "Z" color grade to be considered a Fancy Color.
Fancy Shape Diamond: Any diamond cut into a shape other than round. Fancy cuts include the Marquise Cut, Asscher, Emerald Cut, Heart Shape, Pear Shape, Keystone, Half Moon, Kite, Triangle, and many others. I've even seen them cut into the shape of Christmas Trees, Horse Heads, Tennis Rackets, etc.
Feathers: These are small fractures in a diamond. In some cases the feather both begins and ends within the diamond's surface and, in other cases, the feather begins inside the diamond and extends to the surface. The term "feather" comes from the fact that, under magnification, these fractures often seem to have an indistinct, feathery shape to them. While the idea of buying a diamond with "fractures" or "cracks" may sound scary, the reality is that, with normal wear and care, most feathers pose no risk to the diamond's stability. Most diamonds with feathers have survived their growth and their journey to the surface intact... once on the surface, they also survived the mining process, as well as the brutal stresses of the diamond cutting process. Though diamonds are certainly not invulnerable to damage, basic consideration to their care and handling during everyday wear will most likely protect them over the course of several human lifetimes.
Finish: This refers to the quality of how the diamond cutter executed the designing, fashioning, and faceting the diamond. If you look at a diamond's grading report, you will see its finish graded according to two separate categories: polish and symmetry
Fire: Also called dispersion. This is the result of the white light returning up from the bottom (pavilion) of the diamond and exiting out through the crown area. As the white light exits the angled crown facets it is spread out into its spectral colors. The larger the crown area the more fire a diamond will have.
Fisheye: A diamond whose pavilion is exceedingly shallow, producing a glassy appearance (a noticeable lack of brilliancy) and the reflection of the girdle that starts to come into view in the table area.
Flat Stone: A Round Brilliant Cut diamond with a very thin crown and pavilion.
Flawless: "FL" in GIA's Clarity Grading System... "no blemishes or inclusions when examined by a skilled grader under 10X magnification". The American Gem Society advocates the use of the term "flawless" by its members, while at the same time denying them the use of the term perfect. The Federal Trade Commission permits the use of the term "flawless," but only if a stone conforms to its definition of the word perfect, without reference to make or color.
Fluorescence: The property in diamonds that makes them glow in ultraviolet light. Also known as photoluminescence. Strong, very strong and sometimes medium blue fluorescence may slightly improve the color appearance of diamonds rated "H" in color or below (I,J,K etc). Strong blue fluorescence in diamonds D to F color may impart a very slightly bluish appearance and may, in turn, detract a few percent from the value of those diamonds. All diamonds will fluoresce when exposed to X-rays and this property is used during the ming process to separate rough diamonds from ore.
Foilback: A faceted glass or quartz stone which has a pavilion that is coated with a silver colored paint to reflect light and act like a mirror. It is commonly seen in costume jewelry. Before, modern, highly reflective cuts were developed, even diamonds were foilbacked.
Four C's: A phrase used to describe the 4 characteristics used to determine a diamond's value. All the characteristics start with the letter "C": Cut, Color, Clarity, and Carat weight.
Fracture: An internal or external break or crack in a diamond that is not in the direction of a cleavage plane. Irregular in shape, they usually appear step-like or as a splinter. An internal fracture is also called a feather... a much nicer term to say that you have a feather in your diamond verses having a crack in your diamond!
Fracture Filling or Fracture Filled Diamond: A diamond enhancement process in which a fracture in a diamond is filled with an artificial substance. The fracture that is filled normally reaches the surface of the diamond or it could be laser drilled and then filled. A Diamond Grading Report cannot be issued for a diamond of this type because its clarity characteristics are not considered permanent.
Full Cut Diamond: A description of a Round Brilliant Cut diamond with 57 or 58 facets. Consisting of 32 crown facets and a table facet above the girdle and 24 pavilion facets and possibly a culet facet below the girdle.
Fuzzy Girdle: Also called a Bearded Girdle. If a diamond is "rounded up" too quickly in the bruting process, the surface of the girdle will lack the smoothness and waxy luster of a finely turned girdle. As a result, numerous minute, hairline fractures that extend a short distance into the stone. The girdle can be polishing of faceted to remove or minimize the fractures.
Diamond Glossary - GG: A grade in GIA's Color Grading System.... at the beginning of the "Near Colorless" category.
Gem / Gemstone: A mineral or organic material with sufficient beauty, rarity, and durability to become desirable enough to be set into items of jewelry.
Gemological Institute of America (GIA): In 1931, Robert M. Shipley founded the Gemological Institute of America in Los Angeles. In the same year, he published his groundbreaking book, Gemology, and by that summer, 250 jewelers had enrolled in his courses. Some would later become instructors and researchers at the Institute. Since that time GIA has become the world's foremost authority in gemology. GIA's mission is to ensure the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism through education, research, laboratory services, and instrument development. GIA was responsible for developing and standardizing the diamond grading system that is used today by nearly all other gem labs.
GIA-GTL, Gemological Institute of America's Gem Trade Lab: The well-respected independent laboratory which grades diamonds and provides other services for the diamond and colored stone trade. GTL has labs in many countries around the world.
Gemologist / Graduate Gemologist: A person who studies gems.... normally a diploma is associated with this title. If there is no diploma then if a person who has a love of gems could be called a "rock hound" or an "amateur" gemologist. A person who has successfully completed recognized courses of study in gem identification, grading and pricing, as well as diamond grading and appraising is a Gemologist. There are many different institutions that can bestow the title of Gemologist.... a "Graduate Gemologist" is mostly associated with the Gemological Institute of America and a "Certified Gemologist" with the American Gem Society. I have the title of GG, so I will show my title as follows- Bud Boland, GG(GIA).
Girdle: The outer edge or the widest part of the diamond forming a band around the stone dividing the upper and lower portions of the diamond. It can be unpolished or polished and faceted and of varying thicknesses. The girdle is generally where the diamond is held into a setting.
Girdle Facets: The 32 triangular facets that adjoin the girdle of a Round Brilliant Cut diamond, 16 above and 16 below the girdle. Also called upper and lower girdle facets, upper and lower break facets, top and bottom half facets, skew facets or cross facets. Facets are sometimes placed directly on the girdle, in which case the stone is usually said to have a "faceted girdle".
Girdle Reflection: When the reflection of the girdle that is viewable inside of the table facet.
Girdle Thickness: The measurement of the girdle and the resulting thickness percentage of the diamond's average girdle diameter or the diamond's width. The girdle is not graded, but rather it is described by its appearance at its thinnest and thickest points. The descriptions of girdle thickness range as follows: Extremely Thin, Very Thin, Thin, Slightly Thin, Medium, Slightly Thick, Thick, Very Thick, or Extremely Thick. The girdle should be just thick enough to protect the diamond in setting and normal wear. For a Round Brilliant Cut diamond the girdle should be from Slightly Thin to Medium to Slightly Thick... anything out of this range is the result of trying to retain weight from the diamond rough. A Fancy Shape Diamond should have thicker girdle area at the points of a Marquise Cut or Pear Shape diamond.
Girdling: One of the initial steps of the fashioning process of a diamond in which the stone is given an outline shape. The stone is held in a lathe, or cutting machine, and another diamond, called a sharp, which is affixed to the end of a long dop that is supported by the hands and under an armpit, is brought to bear against the stone behind shaped. An older method consisted merely of rubbing two diamonds together until the desired outline shape was obtained.
Good Cut: An acceptable, lower priced diamond with adequate proportions.
Gold: A precious metal which has been used in jewelry for centuries. Gold will never tarnish, rust or corrode. It has also been used as a store of value to build wealth and shield against hard times. Gold used in jewelry is almost always alloyed with other metals since gold in its pure form is very soft and malleable, and would not wear well by itself.
Grading Report: Sometimes called a "certificate" or a "cert", although labs do not "certify" diamonds. The grading report, issued by an independent laboratory, should accurately describe the measurements, proportions, weight, color, clarity, symmetry, polish and possible fluorescence seen in the diamond being evaluated. Some labs such as GIA and AGS are felt by many experts to be more consistent and stringent in their grading than some other labs.
Grain Center: A small area of concentrated crystal structure distortion, usually associated with pinpoints.
Grain and Grainer: A trade term referring to a diamond's weight. A grain is equivalent to 0.25 carats.... so a 4 grainer = 1.00ct., a 5 grainer = 1.25ct., etc.
Graining: A clarity characteristic resulting from irregularities in the growth direction of a diamond crystal. Appears as faint single line or groups of lines. Much like the grain seen in a piece of wood.
Diamond Glossary - HH: A grade in GIA's Color Grading System.... in the middle of the "Near Colorless" category.
Hardness: The resistance of a substance to being scratched. Mohs scale of relative hardness consists of 10 minerals, each scratching all those below it in scale and being scratched by all those above it. Diamond is 10 on the Mohs scale of hardness, meaning that the only thing that can scratch a diamond is another diamond. Tests prove that diamond is approximately five to 150 times as hard as corundum, the next hardest mineral.
Head: The metal basket which holds the diamond in place with prongs. The head is attached to the ring, earrings, pendant, etc.
Heart Shaped Diamond: A fancy diamond cut, which is cut to resemble the popular Valentine's Day heart shape. It is a modified brilliant cut with a heart-shaped girdle outline that is similar to the Pear Shape Diamond, except that there is a cleft at the top. In fact, often the reason diamond cutters may choose a Heart Shape over a Pear Shape may be that the rough diamond contained an inclusion located in the cleft. The skill of the cutter can make a great difference in the beauty of this cut.
Hearts & Arrows: A Round Brilliant Cut diamond that is cut and polished to ideal proportions with exceptional symmetry and polish which shows eight heart shapes (Pavilion view) and eight arrows (Crown view) when observed through a special viewer called a FireScope. There is no industry standard of diamond proportions.
HRD: Hoge Raad voor Diamant (HRD). HRD Antwerp (Belgium) operates six services: HRD Diamond Lab, HRD Precious Stones Lab, HRD Education, HRD Graduates Club, HRD Equipment and HRD Research. Certification company Diamond High Council.
Hue: A term used to describe the pure spectral sensation of color. Hues include gradations and mixtures of red, organe, yellow, green, blue, violet and purple.
Diamond Glossary - II: A grade in GIA's Color Grading System.... in the middle of the "Near Colorless" category.
Ideal Cut: A Round Brilliant Cut diamond that cut to optimal proportions, with optimal polish and symmetry. There is no universally accepted standard for an Ideal Cut. The most commonly mentioned proportions when talking about an Ideal Cut is the proportioning that was mathematically determined by Marcel Tolkowsky in 1919. See Diamond Cut
IGI: International Gemological Institute. A gemological laboratory which offers a diamond grading reports also written appraisals.
Illusion setting: A head designed to make the diamond that is set into it look larger than it actually is.... hence it is giving the "illusion" of a larger diamond. The metal that surrounds the stone usually has an intricate design.
Included (I1,I2,I3): "I" in GIA's Clarity Grading System... "contain inclusions which are obvious to a trained grader under 10X, can often be easily seen face-up with the unaided eye, seriously affect the stone's potential durability, or are so numerous they affect transparency and brilliance". I1 usually has inclusions that are visible to the unaided eye and at the end of the I3 grade the diamond can no longer be considered gem quality.
Included Crystal: A mineral crystal (many times it's another diamond, but it could also be one of many different minerals) contained inside of a diamond. Include crystals can be almost any size, colored or colorless, and can occur alone or in groups. Dark included crystals are often called "carbon spots" or just "carbon", but it's an incorrect term when referring to these diamond inclusions.
Inclusions: This is all the fun stuff inside of your diamond.... things that are included inside of your diamond at no additional charge! These are clarity characteristics found within most diamonds and they could almost be considered a fingerprint because the inclusions in each diamond can be very different. Most inclusions were created when the gem first formed in the earth billions of years ago. Common diamond inclusions include feathers, crystals, fractures, graining, pinpoints, and cavities.
Internal Graining: Internal indications of irregular crystal growth. May appear milky, like faint lines or streaks, or may be colored or reflective.
Internally Flawless: "IF" in GIA's Clarity Grading System... "no inclusions when examined by a skilled grader, and only insignificant blemishes under 10X".
Industrial Diamonds: Non-gem quality diamonds used in drills and other tools.
Invisible Set Diamonds: A skilled method of setting square gemstones into two rows or more with no metal showing between the rows.
Irradiated Diamond: A diamond which has been exposed to a stream of accelerated electrons and then heated in order to alter its color. See Color Enhanced Diamonds.
Diamond Glossary - JJ: A grade in GIA's Color Grading System.... at the end of the "Near Colorless" category.
I guess J is not a popular letter in the diamond business!
Maybe, I could tell a Joke, or I could Juggle, or I guess we could Just move on to K.....
Diamond Glossary - KK: A grade in GIA's Color Grading System.... at the beginning of the "Faint Yellow" category.
Karat: The measure of purity of gold... 24K gold is 100% pure, 18K gold is 75% pure, 14K gold is 58.5% pure.
Kimberlite: Volcanic diamond bearing rock (also called blueground by the miners). These Kimberlite pipes are the primary source for diamonds. Open pit mines are started at the top of the pipe and vertical shafts are sunk down along the sides and then horizontal tunnels are then dug to access the pipe at greater depths.
Kimberly Process: Also referred to as KPCS- Kimberley Process Certification Scheme. The Kimberley Process (KP) is a joint governments, industry and civil society initiative to stem the flow of conflict diamonds (rough diamonds used by rebel movements to finance wars against legitimate governments). The trade in these illicit stones has fuelled decades of devastating conflicts in countries such as Angola, Cote d'Ivoire, the Democratic Republic of the Congo and Sierra Leone.
Knife-edge Girdle: A girdle of a diamond that is so thin that it can be likened to the edge of a sharp knife. This is a sign of poor cutting since such a girdle is easily chipped.
Knot: An included diamond crystal that is encountered by the saw blade while the diamond rough is being sawn in half. Also an included diamond crystal that is encountered at the surface of a diamond during the polishing operation, and that stands out as a small, raised surface on the finished diamond. This is just like a knot in a piece of wood.
Diamond Glossary - LL: A grade in GIA's Color Grading System.... in the middle of the "Faint Yellow" category.
Laser Cutting: Diamond has different directions that it can be cleaved, sawn, and polished. Using a laser to cut the diamond into an unusual shape is now possible. A laser can cut across the growth plains, which makes odd shapes such as letters, Christmas trees, tennis rackets, horse heads, etc. possible.
Laser Drill Hole: A hole is a tiny tunnel drilled into a diamond by a laser beam. The tunnel extends from the surface of a diamond down to a dark included crystal. The diamond is laser drilled in order to lighten a dark included crystal. After the diamond has been drilled the inclusion can be then bleached and become less noticeable. It might improve the clarity grade of the diamond but it usually will make a diamond much more marketable having a lightly colored inclusion verses a much more obvious darker inclusion. GIA's Gem Trade Lab will issue a diamond grading report on diamonds that have laser drill holes (without any fracture filling) because the holes are permanent features and they will note the laser drill holes under the comments area of the report.
Laser Inscription: An extremely small inscription by a laser along the girdle of a diamond. This can be the diamond grading report number, a logo, a message, or a company's name.
Length-to-Width Ratio: A ratio of how many times greater the length is in comparison to the width of a fancy shape diamond. Each fancy shape diamond has a range of ratios that are acceptable by most people. There is no "ideal" L to W ratio.... some are considered to be more appealing but it does turn out to be a personal preference.
Leveridge Gauge: A commonly used device to measure the precise dimensions of a mounted or unmounted gemstones.
Light Yellow: A trade term used by some dealers to cover a wide range of colors in the low end of the diamond color-grading scale. Diamonds with a "touch of warmth".
Lively Stone: A diamond that has a reasonably good cut so that it has good brilliance and luster.
Lot: A large group of diamonds that have been closely matched in clarity, color, cut, and weight.... these diamonds are being offered for sale as an entire group and not piece by piece.
Loupe: A handheld magnifying glass used in the diamond trade to inspect diamonds. Magnification is usually 10X power and is corrected so as not to distort shapes and color. All diamonds are clarity graded under 10X.
Loupe Clean: When viewed under 10X magnification, a diamond is considered loupe clean if no obvious inclusions are immediately seen.
Lower Girdle Facets: These are triangular shaped facets, located on the pavilion just below the girdle.
Luster: The quality and quantity of reflected light from the surface of a gemstone. Because of its hardness, diamond has an "adamantine luster".
Diamond Glossary - MM: A grade in GIA's Color Grading System.... at the end of the "Faint Yellow" category.
Main Facets: The 8 crown and the 8 pavilion facets of a Brilliant Cut diamond. These are the facets where the angles are measured in order to determine a diamonds proportions.
Make: A trade term referring to the proportions, symmetry, and polish of a diamond. Commonly stated as a "good make", "well made", a "poor make", etc.
Marquise Cut Diamond: A Fancy Shape diamond which is "boat shaped", elongated with points at each end. The term "Marquise" came from a story about the origins of the shape. The French "le Roi Soleil", Louis XIV wanted a diamond to be polished into the shape of the mouth of the Marquise of Pompadour.
Master Stones: A set of diamonds of known color that are used to decide the body color of other diamonds that are compared to this set of master diamonds. A set of master stones must have very exacting specifications in order to be used.
Melee: A French word meaning confused mass. A trade term that is used to describe small diamonds. They are usually side diamonds or accent diamonds in a piece of jewelry.
Mixed Cut: This faceting style has both step-cut (crown, top) and brilliant-cut (pavilion, bottom) facets.
Mohs Scale: In 1812, a scale of mineral hardness was devised by the German mineralogist Friedrich Mohs, who selected the ten minerals because they were common or readily available. The scale is not a linear scale, but somewhat arbitrary. The scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material.
The comparative scale of hardness is as follows:
8) topaz and beryl
Mounting: Trade term for a piece of jewelry in which a gem or other object is set.
Diamond Glossary - NN: A grade in GIA's Color Grading System.... at the beginning of the "Very Light Yellow" category.
Natural: A portion of the original "skin" of a rough diamond that is left by the diamond cutter on a faceted diamond. Naturals are usually found along the girdle. In many cases, naturals do not affect the clarity grade.
Navette: A French word meaning "little boat". A Marquise Cut diamond.
Near Colorless: A general term for diamonds in the G-to-J color range.
Needle: A long, thin included crystal which looks like a.... needle.
Nick: A minor chip out of the surface of a fashioned diamond, usually caused by a light blow. Could be found along the girdle or facet junctions.
Diamond Glossary - OO: A grade in GIA's Color Grading System.... at the beginning of the "Very Light Yellow" category.
Off Center Culet: This is a problem with the symmetry of a diamond... the culet is not lined up with the center of the table. The culet has been pushed over to one side of the diamond. It was intentionally done in order to repair damage to a previously polished diamond or from attempting to retain maximum weight from a distorted piece of diamond rough.
Off Make: A trade term for a poorly proportioned Diamond.
Old European Cut: An early form of the Round Brilliant Cut diamond characterized by a small table, a high crown, deeper pavilion, and a large culet. Contrary to what you initially might have thought, it is not a diamond that was cut by an old European.
Old Mine Cut: A diamond cut that pre-dates the Old European Cut with the primary difference being the overall shape of the diamond was squarish.... similar to today's Cushion Cut diamond.
Open Table: A term that is sometimes used to refer to a diamond with a table of 65% or more.
Oval Cut: The famous diamond cutting house of Lazare Kaplan developed the Oval Shape Diamond in the early 1960's. This is a brilliant style of faceting and is an elliptical variation of the traditional round brilliant cut.
Diamond Glossary - PP: A grade in GIA's Color Grading System.... in the middle of the "Very Light Yellow" category.
pc: Abbreviation for "per carat" pricing.... expressed as $750pc.
Parcel Paper: Also called diamond papers. Folded sheets of paper used to contain polished or rough diamonds. On the outside of the paper are many different numbers- such as stock number, clarity, color, carat weight, shape, supplier, cost, etc. Contrary to what you see in the movies.... diamonds are not kept in big piles in boxes and trays... they are kept in papers.
Patina: A sheen which develops on the surface of platinum jewelry through continued wear.
Paste: A term for glass imitation gemstones.
Pave: (pah-VAY) A style of setting small stones very tightly together, as in a pavement or paved with diamonds. Most commonly seen with diamonds, but may be used with any stone.
Pavilion: The bottom portion of a diamond, below the girdle, measuring from the girdle down to the culet.
Pavilion Angle: The angle measured between the girdle plane and the pavilion main facet.
Pavilion Main Facet: Eight, four sided facets of a Round Brilliant Cut diamond that meet at a point to form the culet.
Pear Cut: A fancy shape diamond that resembles a teardrop or pear. The Pear Shape is a combination of the Oval Shape and the Marquise Cut.
Perfect: This term has been so flagrantly misused in the sale of diamonds that many jewelers avoid its use entirely. The American Gem Society also prohibits its use by its members. The Federal Trade Commission considers it an unfair trade practice to use the word "perfect", or any other word, expression or representation of similar import, as descriptive of any diamond that discloses flaws, cracks, carbon spots, clouds or other blemishes or imperfections of any kind, including inferior color and make, when examined by a trained eye under a corrected diamond eye loupe or other equal magnifier of not less than ten power.
Pinpoint: A pinpoint is a extremely small included crystal inside of a diamond. A grouping of pinpoints is called a "cloud". A cloud can appear as a hazy area in the diamond. A single pinpoint can change a diamond clarity grade from an Internally Flawless to a VVS1.
Pipe: The remains of an ancient volcano. Diamond bearing magma (kimberlite) had made its way to the surface via a weak spot in the earth's crust. The volcanic mountain that was formed is then eroded away from rain and all that is left is the pipe. Open pit mining is done on top of the pipe and a vertical shaft is sunk next to the pipe with horizontal tunnels dug into the pipe. Kimberlite pipes have been found in Africa, Canada, Russia, Arkansas, Australia, and elsewhere.
Pit: A tiny opening on the surface of a diamond, often looking like a white dot.
Platinum: A rare precious metal used in jewelry. Platinum is naturally white and is favored for many ring settings because of its durability.
Plotting Diagram: A diagram used on some Diamond Grading Reports that illustrates the facets of a diamond and the approximate location and type of internal and external characteristics.
Point: A trade term used to describe the weight of diamonds. One point is equivalent to one-hundredth of a carat. For example, a 1/4 carat diamond, equals 0.25ct., equals 25 points.
Pointer: Term used to describe polished stones under a carat. For example, a 37 pointer (0.37ct.).
Polish: The smoothness of the surface of a diamond which shows no visible wheel or burn marks. Polish is regarded as one of the indicators of the quality of as diamond's cut; it is graded as either Ideal, Excellent, Very Good, Good, Fair, or Poor.
Polish Lines: Tiny parallel lines left by irregularities in the diamond cutting wheeel's surface.
Polish Mark: Surface clouding caused by excessive heat (also called burn mark, or burned facet), or uneven polished surface resulting from structural irregularities.
Polishing: In diamond fashioning, it is used to include both lapping, or blocking, and brillianteering, as well as the production of any facet; the final operation in fashioning a diamond, usually done with diamond powder on a horizontal disc, or lap, against which the diamond is held in a dop.
Polished Girdle: A girdle that has been lapped or polished to yield a uniform, highly reflective surface.
Poor Cut: A inferior cut diamond that can be either cut too deep or too shallow which will lose or leak light through the side or bottom resulting in less brilliance and value.
Princess Cut: A square or rectangular-shaped modified brilliant cut diamond.
Prong or Claw Setting: A setting style that uses 4 or 6 small fingers of metal that hold a diamond in place. Each metal prong is individually pushed into place to hold the diamond securely.
Proportion: The proportions of a diamond are very important, so that the maximum amount of light be reflected off and out of a stone. Proportion is the relationship between the angles of the facets of the crown and pavillion.
Proportion Scope: A device that combines lenses and movable mirrors to project the silhouette of a diamond onto a screen. Diagrams and scales are printed on the screen which facilitates the analyzation of the proportions of round brilliant cut diamonds, as well as fancy shaped diamonds.
Diamond Glossary - QQ: A grade in GIA's Color Grading System.... at the end of the "Very Light Yellow" category.
Quality: Term used to describe the degree of excellence of a diamond by its weight, color, clarity, and perfection of cut.
Diamond Glossary - RR: A grade in GIA's Color Grading System.... at the end of the "Very Light Yellow" category.
Radiant Cut: A brilliant cut fancy shape that has a square shape with the corners cut off. It might have a step cut or a scissor cut on the crown and a brilliant faceting style on the pavilion.
Reflection: The bouncing back of light when it strikes an external or internal facet on a polished diamond.
Refraction: The change in direction of a ray of light as it passes obliquely from a medium of one optical density to a medium of a different optical density, as from air into water or from air into a gemstone. This means that the light bends as it enters a diamond because the light travels through air and the diamond at different speeds.
Rhinestone: A facetted piece of glass or quartz that has a foil backing in order to imitate a diamond.
Rhodium Plating: Rhodium is metal that is part of the platinum family. White gold is commonly rhodium plated in order to give it a very white finished color because white gold is not purely white but instead has a yellowish tint It is also used on silver to prevent it from oxidizing.
Rose Cut: An early style of cutting that is thought to have originated in India and to have been brought to Europe by the Venetians. In its most usual form, it has a flat, unfaceted base and a somewhat dome-shaped top that is covered with a varied number of triangular facets and terminates in a point. The rose cut diamonds are very seldom used today but may be seen in antique pieces.
Rough: An unpolished diamond in its natural crystal shape.
Rough Girdle: When a diamond outer shape is formed in the cutting process it is done by grinding one diamond against another. This should leave the surface of the girdle with a smooth and waxy luster. If a diamond is rounded up too quickly in the fashioning process it will leave it grainy or pitted. It may also be accompanied by numerous hair like fractures extending into the stone, which is called a bearded or fuzzy girdle.
Round Brilliant Cut: This is the most common cut for a diamond. The standard round brilliant "full cut" diamond consists of a total of 58 facets: 1 table, 8 bezel facets, 8 star facets and 16 upper-girdle facets on the crown; and 8 pavilion facets, 16 lower-girdle facets, and usually a culet on the pavilion.
Rounding Up or Girdling: The step in the fashioning process of a diamond in which the stone is given its overall shape. The stone is held in a lathe, or cutting machine, and another diamond, called a sharp, which is affixed to the end of a long dop that is supported by the hands and under an armpit, is brought to bear against the stone behind shaped. An older method consisted merely of rubbing two diamonds together until the desired shape was obtained.
Diamond Glossary - SS: A grade in GIA's Color Grading System.... at the beginning of the "Light Yellow" category.
Sawyer: A person who has the job of sawing diamonds.
Sawable: These are rough diamonds that can be divided by sawing.
Scaife: The horizontal cutting wheel on which a diamond is polished... also spelled scaive or scaif.
Scratch: A fine white line, curved or straight on the surface of a diamond. A scratch would be considered during the clarity grading process. A scratch can be polished away.
Scintillation: The flashes of light reflected off of the facets of a diamond when the diamond or the eye of the viewer moves. This is the bling factor! The number, the size, and the quality of the polish of the facets are all factors in the scintillation.
Spread Stone: A diamond with a large table.
Set: How a diamond is held into a piece of jewelry. For example... bead set, pave set, channel set, prong set, etc.
Setting: A metal holder for the diamond.
Skin: The surface of an unpolished diamond.
Sorter: The person who separates rough diamonds into sizes and grades of quality by shape, color, and clarity.
Star Facets: The eight triangular facets around the table of a diamond that make it star-shaped.
Surface Graining: An area of crystal growth irregularity that does not polish the same direction as the surrounding area. Much the same as grain in wood.
Semi-mount: A jewelry setting that has the side stones already mounted, but which contains an empty set of prongs which are intended to mount a diamond center stone.
Single Cut: A round diamond with only 17 or 18 facets, instead of the normal 57 or 58 facets of a full cut diamond.
Step Cut: Broad, flat facets that resemble stair steps. Emerald Cut or Asscher Cut Diamonds are cut in this style.
Symmetry: The misalignment of facets or facets that fail to point correctly to the girdle. Symmetry is regarded as an indicator of the quality of the Diamond Cutter's care and skill in fashioning the diamond. It is graded as either Ideal, Excellent, Very Good, Good, Fair or Poor.
60/60: An incorrect guideline that is sometimes referred to, stating that a diamond with a 60% Depth and a 60% Table is a diamond with good proportions. More information would be needed in addition to these 2 bits of information before you would be able to make any judgement about the diamond.
Diamond Glossary - TT: A grade in GIA's Color Grading System.... at the beginning of the "Light Yellow" category.
Table: is the large facet on the top of the diamond's crown.Table - The flat facet on the top of the diamond. It is the largest facet on a cut diamond.Table: The flat facet on the top of the diamond. It is the largest facet on a cut diamond.
Table Percentage: The relationship of the table as compared to the average diameter of a round brilliant cut or the width of a fancy shape diamond. So, a diamond with a 60% table has a table which is 60% as wide as the diamond's outline.
Treated Diamond: describes a polished diamond that has been altered to change its appearance, (e.g., by artificial coloration, that is, irradiation).
Trilliant Cut: A brilliant cut fancy shape that is triangular.
Twinning Wisp: A cloudy area produced by crystal structure distortion, usually associated with twinning planes.
Diamond Glossary - UU: A grade in GIA's Color Grading System.... at the beginning of the "Light Yellow" category.
Uncut or Unpolished Diamonds: Diamonds that are usually referred to as "rough" or "diamond rough"... diamonds are they are found in the earth. It applies to all diamonds that have not been cut and polished yet.
Upper Girdle Facets: These are 16 triangular shaped facets, that are located on the crown just above the girdle.
Ultraviolet Fluorescence: The property in diamonds that makes them glow in ultraviolet light. Also known as photoluminescence. Ultraviolet light is high frequency, short wavelength electromagnetic radiation, between visible light and X-rays.
Unmounted: A faceted diamond which is loose, not set into a piece of jewelry.
Diamond Glossary - VV: A grade in GIA's Color Grading System.... in the middle of the "Light Yellow" category.
VS1, VS2: Clarity grades for diamonds developed by the Gemological Institute of America, just below Very Very Slightly Included (VVS). VS- Very Slightly Included, contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) for a trained grader to see under 10X.
VVS1, VVS2: Clarity grades for diamonds developed by the Gemological Institute of America, just below Internally Flawless (IF). VVS- Very Very Slightly Included, contain minute inclusions that are difficult for even a skilled grader to locate under 10X. VVS1: extremely difficult to see, visible only from the pavilion or small and shallow enough to be removed by minor repolishing. VVS2: very difficult to see.
Vivid: Used on color grading of fancy colored diamonds to denote the most intensely colored stones, not the darkest.
Diamond Glossary - WW: A grade in GIA's Color Grading System.... in the middle of the "Light Yellow" category.
West 47th Street: "Diamond Jewelry Way" is the central location of the diamond industry in New York.
Wetability: Diamond is highly resistant to wetting by water.
White: A term that refers to a colorless diamond. Actually it is a colorless diamond so it technically can't be white
White Light: Light containing a balanced full spectrum of colors, so that it appears colorless. Traditionally, in the North Hemisphere it has been light coming in a window that faces north (in the Southern Hemisphere would be the south) this light source would be considered balanced enough for good consistent results. Today it is possible to have color balanced fluorescent lights that make it possible to have this balance white light that is important for diamond color grading.
Window: A small facet polished on a rough diamond, through its skin, to allow a diamanteer to observe and map any internal features of the diamond prior to cutting. Also an area of a gemstone which "leaks" light or color usually due to poor, often shallow, cutting.
Windowing Out: A trade term describing when the viewer is able to see through a gemstone as it is tilted to the side. The pavilion should act like a mirror and not like a window.
Harry Winston: A famous Beverley Hills jeweler who is known as the "Jeweler to the Stars". There are now many Harry Winston store around the world.
Wisp: An clarity feature due to twinning which is an irregularity in the crystal growth.
Diamond Glossary - X-Y-ZX: A grade in GIA's Color Grading System.... at the end of the "Light Yellow" category.
X-ray Fluorescence: The property in diamonds that makes them glow when exposed to X-rays. All diamonds will fluoresce when exposed to X-rays and this property is used during the mining process to separate rough diamonds from ore.
Y: A grade in GIA's Color Grading System.... at the end of the "Light Yellow" category.
YAG: Yttrium Aluminium Garnet, used as a somewhat unconvincing diamond simulant before Cubic Zirconia.
Yellow: Most diamonds contain nitrogen which gives them a slight yellow, "touch of warmth".
Yellow Ground: The usual diamond bearing rock in which diamonds are found is called Kimberlite or blue ground. As this rock is exposed to sunlight and the weather elements is begins to decompose and its color changes from blue to yellow. This yellow ground is easier to break apart in the search for diamond rough.
Z: A grade in GIA's Color Grading System.... at the end of the "Light Yellow" category. The next color grade for a yellow diamond will put it into the "Fancy (Color) Diamond" category and the price will begin to rise.
Zaire: The former name of the Democratic Republic of the Congo used from 1965 to 1997. Produces a large proportion of the world production of industrial grade diamonds.
Zirconia: Zirconium Oxide, or more accurately Zirconium Dioxide, also called zirconia, when crystallised in cubic system, it is known as Cubic Zirconia. Although this is found in nature, most Cubic Zirconia is made in the lab... hence it is should be more correctly called Synthetic Cubic Zirconia.
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