AGS - American Gem Society, a professional society created to aide in the promotion of high standards of ethics, education and service.
Blemish - an external flaw (scratch or abrasion) on the surface of a diamond, usually only affecting the polish grade.
Brilliance - white light reflected up through the surface of a diamond.
Brilliant Cut - cut with facet arrangement radiating out from the center, utilizing triangular or kite-shaped facets.
Bearding - tiny feathers extending in from the girdle edge.
Bruise - surface crumbling, often accompanied by tiny, root-like feathers.
Bruting - Cutting step involving rough diamonds which produces the basic shape outline.
Carat - a standard unit of measure for diamonds and other gemstones. One carat is usually expressed as 100 points, a 0.50 ct. as 50 points, etc.
Cavity - a large or deep opening on the surface of a stone, usually angular in appearance.
Chip - a small, large, deep or shallow opening, usually curved or rounded in appearance, often at the girdle edge.
Clarity - the degree to which a diamond is free from inclusions and blemishes.
Clarity Enhancement - an artificial process for improving the clarity of a stone.
Cleavage - an internal growth characteristic that runs in the direction of the grain of the diamond.
Cloud - a group of very small pinpoint inclusions that can be confined to a small area or spread throughout the stone. In some cases, may cause a milky or hazy appearance.
Color - the relative position of a diamond's body color on a colorless to light yellow scale, denoted by letters (i.e., D to Z, where D is colorless and Z is light yellow) on the GIA color scale, or by numbers (i.e., 0 to 10, where 0 is colorless and 10 is light yellow) on the AGS color scale.
Color Enhancement - laboratory processes ranging from a simple colored coating to a sophisticated permanent alteration of certain trace elements naturally found in a diamond.
Culet - a facet which is usually placed on the point of the pavilion mainly for protection from chipping. The culets of older, European-cut diamonds can be seen through the table of the diamond and appear as round, glassy discs. The preferred culet is visible only as a tiny focal point where the facets of the pavilion converge.
Cut - commonly used to refer to both the outline shape of a stone (round, pear, oval, etc.) and cutting proportions.
Cutting Style - faceting arrangement utilized in fashioning a gemstone, i.e., brilliant cut, step-cut or mixed-cut.
Depth - the height of a diamond (measured from the culet to the table).
Depth Percentage (%) - the depth of a diamond divided by the width of the diamond.
Dispersion - (See Fire)
