Diamond Terms iframe

Diamond Terms iframe

AGS  American Gem Society; 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).

Brightness  Sometimes called brilliance, is the level of light that radiates up from within the diamond just as a spotlight gets brighter by twisting its dimmer switch. Brightness can best be understood by viewing a diagram of a diamond’s silhouette.

Carat weight  Weight of measure for a diamond. One carat is equal to approximately one-fifth of a gram.

Color  The absence of body tone. Graded on a scale of D-Z, the “best” color for a diamond is D, “Colorless.”

Culet  The bottom facet of a diamond. If the bottom of a diamond comes to a complete point then there is no culet. If it has a very small flat surface (almost imperceptible) then it has a culet.

Cut  The level of design and craftsmanship of transforming a diamond from a raw crystal to a polished gem.

Design  Describes the brightness, weight-ratio, fire and scintillation of the diamond for round diamonds. For fancy-shaped diamonds, design also includes proper scale of the overall shape.

Durability  The diamond’s likelihood of resisting chipping or breaking.

Fancy-shape  Diamond shape other than round.

Fire  Sometimes called dispersion, describes the colors-of-a-rainbow that appear in a diamond.

Fluorescence  The blue “glow-in-the-dark” effect that some diamonds have when exposed to ultraviolet light just like some posters near “black-light” lamps.

GIA  Gemological Institute of America. Established in 1931, GIA is the world’s largest and most respected nonprofit institute of gemological research and learning.

Grading Report  Document that is provided with a loose diamond containing the diamond’s attributes.

Hue  The GIA specifies 31 gemstone hues. They include terms such as blue, slightly greenish blue, very slightly greenish blue, bluish green, etc.

Polish  Polish describes the quality of a diamond’s surface. Individual surfaces must join invisibly, with seamless edges, so that the diamond appears as a solid monolith.

Purity  The natural birthmarks that are formed within the diamond as nature transforms it from a lump of coal (carbon) into a magnificent crystal.

Saturation  This is the degree to which a color departs from a neutral (gray) sensation. Saturation can be thought of as the relative purity of a hue. The GIA specifies 9 terms, such as brownish, grayish, moderately strong, and vivid.

Scintillation  Describes the sparkling or twinkling effect given off as diamonds are moving about. It looks as if you are seeing bright white flashes of mini-fireworks within the diamond.

Shape  Pattern of a cut diamond when viewed from the top.

Silhouette  The shape you see when viewing a diamond from the side.

Symmetry  The alignment of the diamond surface (facets).

Temperature  A measure of the distribution of power in the spectrum of white, or colorless, light, stated in terms of the Kelvin temperature scale.

Weight-ratio  The relationship between the diamond size (viewed from the top) and its weight.

Workmanship  Describes the symmetry, polish, and durability of the diamond.