Common Terminology or Trade Terms

Baguette– A French word meaning “rod” .A style of step cutting for small, rectangular or trapeze-shaped gemstones, principally diamonds.

Bearded Girdle– If a diamond is rounded up too quickly in the fashioning process, the surface of the girdle will lack the smoothness and waxy luster of a finely turned girdle. Consequently, numerous minute, hairline fractures extend a short distance into the stone. A girdle with this appearance is referred to as being “bearded” or “fuzzy.”.

Blue White– A term banned by the FTC except in cases in which a diamond is graded D,E,or F colour with a blue fluorescence.

Body Color– The colour of a diamond as observed when examined under a diffused light against a hueless background free from surrounding reflections. The diffused light eliminates glaring reflections and dispersion, which would otherwise confuse the colour determination.

Brilliance– The intensity of the internal and external reflections of white light to the eye from a diamond or other gem in the face-up position. It is not to be confused with scintillation or dispersion.

Brilliant Cut– The most common style of cutting for both diamonds and colored stones. The standard round brilliant 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, or base. Although the brilliant style was devised to give maximum brilliancy and fire, many stones cut in this fashion do not have ideal proportions or angles for that purpose. Modifications of the round brilliant include such fancy shapes as the marquise, half moon, pear shape and many others.

Canary Diamond– An intensely coloured, yellow diamond. The yellow may be very slightly greenish or slightly orangey, but it must be deep enough to be a distinct asset. Such a diamond is called a fancy. This term is often misused to denote any yellow diamond. The deciding factor is the orangey or greenish hue.

Carat– A unit of weight for diamonds and other gems. The carat formerly varied somewhat in different countries, but the metric carat of .200 grams, or 200 milligrams, was adopted in the United States in 1913 and is now standardized in the principal countries of the world. There are 100 points in a carat. It is sometimes incorrectly spelled “karat”but in the USA karat refers only to the fineness of pure gold and gold alloys.

Carbon Spots– Any black-appearing inclusion or imperfection in a diamond. Actually, true carbon inclusions are rare, although some may occasionally be graphite or small particles of another mineral. Although many diamond contain inclusions that appear black under ordinary lighting, dark-filled illumination, plus magnification, shows most to be caused by reflection from cleavages or included transparent diamond crystals or other transparent minerals. This term is often mis-used and the more-informed jewelers never use it.

Certified Gemologist– A title awarded by the American Gem Society to qualified jeweler-members. To qualify, a person must study colored stones and their identification and diamond grading and appraising. Also, he must prove his proficiency with several written examinations, a diamond-grading examination, and pass a 20-stone gem-testing examination without error. This is the AGS’s most advanced title. See: Gemologist.

Chip– (a) A curved break on a diamond that extends from a surface edge. (b) A small rose-cut diamond or single-cut melee. (c) A cleavage piece of diamond that weighs less than one carat. (d) A small, irregularly shaped diamond. Usually only very old jewelry would be set with true chips. Modern jewelry contains full or single cut melee.

Cooked– Any coloured stone that has been heat treated.

Crown– That part of any fashioned gemstone above the girdle.

Culet– The small facet that is polished parallel to the girdle plane across what would otherwise be the sharp point or ridge that terminates the pavilion of a diamond or other gemstone. Its function is to reduce the possibility of damage to the stone.

Depth Percentage– The depth of a stone measured from the table to the culet, expressed as a percentage of the stone’s diameter at the girdle, is a relationship used in the analysis of the proportions of a fashioned diamond.

Dispersion– The property of transparent gemstones to separate white light into the colors of the spectrum. The interval between such colors varies in different gemstones, but in practice it is measure by the difference between the refractive indices of the red and blue rays. Diamond has the highest dispersion (.044) of any natural, colourless gem.

Eye Clean– A term used to imply that no internal flaws are visible to the unaided eye of a qualified diamond-clarity grader. 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.

Four Grainer– A term used to denote and stone that weighs approximately 1 ct. A two grainer would be ½ ct. A six grainer would be 1 ½ ct.

Full Cut-Any diamond with 57 or 58 facets.

Fuzzy Girdle or Bearded Girdle– If a diamond is rounded up too quickly in the fashioning process, the surface of the girdle will lack the smoothness and waxy luster of a finely turned girdle. Consequently, numerous minute, hairline fractures extend a short distance into the stone. A girdle with this appearance is referred to as being “bearded” or “fuzzy”.

Fancy Cut– Any style of diamond cutting other than the round brilliant or single cut. Fancy cuts include the marquise, emerald cut, heart shape, pear shape, keystone, half moon, kite, triangle, and many others. Also called the fancy-shaped diamond or modern cut.

Fancy Diamond– Any diamond with a natural body colour strong enough to be attractive, rather than off colour. Reddish (the pure red of ruby is extremely rare), blue and green are very rare; orange and violet, rare; strong yellow, yellowish-green brown and black stones are more common.

Fire– Flashes of different spectrum colors seen in diamonds and other gemstones as the result of dispersion.

Fisheye– A diamond whose pavilion is exceedingly shallow, producing a glassy appearance and a noticeable dearth of brilliancy.

Flat Stone– A diamond brilliant with a very thin crown and pavilion.

Gemologist– One who has successfully completed recognized courses of study in gem identification, grading and pricing, as well as diamond grading and appraising; e.g., a Gemologist or Graduate Gemologist of the Gemological Institute of America or a Certified Gemologist of the American Gem Society.

Girdle– The outer edge, or periphery, of a fashioned stone. It is the portion that is usually grasped by the setting or mounting; the dividing line between the crown and pavilion.

Ideal Cut or American Cut– Those proportions and facet angles calculated mathematically by Marcel Tolkowsky to produce maximum brilliancy consistent with a high degree of fire in a round diamond brilliant are considered by many diamond men to constitute the ideal cut. These figures, computed as a percentage of the girdle diameter, are as follows: total depth, 59.3% (without provision for girdle thickness); crown depth, 16.2%; pavilion depth, 43.1%. The bezel angle is 34° and the pavilion angle is 40°. Girdle thickness as a percentage of the girdle’s diameter varies with size. The larger the stone, the smaller the percentage for a medium girdle. The variation is from about 1% to 3%.

Light Yellow– A trade term used by some dealers to cover a wide range of colours in the low end of the diamond color-grading scale. Stones in the broad classification show a very obvious yellow tint to the unaided eye.

Lot– (a) A group of rough diamonds offered for sale by the Diamond Trading Co. to firms invited to view its sights. A “lot” usually includes a wide variety of material. (b) Also applied by diamond and coloured stone merchants to their regroupings of these stones according to color, make, and comparative freedom from imperfections after fashioning. Jewelry stores and manufacturers can buy “lots” of stones for a lower price than buying individual stones.

Melee– From the French, meaning confused mass. (a) In the trade, the term is used collectively to describe small (up to .20 or .25 carat) brilliant-cut diamonds, whether full cut or not. Usually, all small gemstones used to embellish mountings, setting or larger gems are called melee.

Pavillion– The portion of the stone below the girdle.

Pigeion Blood red or Cornflower Blue– Old terms used to designate the finest colours of ruby or blue sapphire. They are generally meaningless in today’s world.

Point– In weighing stones, one-hundredth part of a carat, each hundredth being called a point; e.g., 32 hundredths (.32) of a carat is said to be a 32-point diamond, or a thirty-two pointer. 100 points = 1 carat.

Single Cut– Any diamond with 17 or 18 facets, usually reserved for melee size stones.

Solitaire– A term used to refer to a ring containing a single diamond or other gem of any shape.

Spread Stone– A term that is used frequently in the diamond trade to refer to a stone that has been cut with a large table and a thin crown, to retain greater weight from the two sawn pieces of an octahedron than is possible by using ideal proportions. In a strict sense, any increase in table diameter over the ideal 53% constitutes spreading; however, it is a general trade practice to apply the term only to those stones with tables that measure in excess of about 65%.


Yantz Bradbury Associates
P.O. Box 10123 –  Rockville, Maryland – 20850  
Office: (301) 335-6687

Serving MD, VA and DC Metro Area

Comments are closed.