Diamond Glossary

The knowledge and more information you have the better diamond purchase you will make. Here are a number of diamond terms that are used by jewelers to describe diamonds and which appear on diamond grading reports.

K:

Knot:
An included diamond crystal that is encountered at the surface of a stone during the polishing operation, and that stands out as a small, raised surface on the finished stone. An included diamond crystal that is encountered by the saw blade. Since the softest directions available for sawing and polishing are used by the cutter, and since included crystals have a different orientation from the surrounding mass, they almost always have a harder direction than that being exploited. A small section of a twinned stone in which the grain differs from the main mass.

Karat:
The fineness of gold, equal to one part of 24 in gold alloys. 14Kt gold is actually just 58.5% fine gold, and the rest various alloys and combinations of metals. 18Kt is 3/4 fine gold or 75%, and the richer color is from this increase in fine gold. White gold is a trick, the alloys fool your eye into seeing white, along with the fact that most manufacturers will also rhodium plate the white areas to enhance their white and brightness

Knife-edge Girdle:
A girdle of a diamond that is so thin that it can be likened to the edge of a sharp knife. Since such a girdle is easily chipped, an ideal girdle has an appreciable thickness. A knife edge girdle would result in a rating of AGS-10 Poor on the AGS Proportions Scale.

Kimberlite:
Volcanic diamond-bearing rock (also called blueground). The complex volcanic magmas that solidify into kimberlite and lamproite are not the source of diamonds, only the elevators that bring them with other minerals and mantle rocks to Earth's surface. Although rising from much greater depths than other magmas, these pipes and volcanic cones are relatively small and rare, but they erupt in extraordinary supersonic explosions.

Kimberlite and lamproite are similar mixtures of rock material. Their important constituents include fragments of rock from Earth's mantle, large crystals, and the crystallized magma that glues the mixture together. The magmas are very rich in magnesium and volatile compounds such as water and carbon dioxide. As the volatiles dissolved in the magma change to gas near Earth's surface, explosive eruptions create the characteristic carrot- or bowl-shaped pipes.

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N:

Naturals:
Small parts of the original rough diamond's surface which are left on the polished diamond, frequently on or near the girdle. While these are blemishes, they might also be regarded as a sign of skilled cutting; the presence of a natural reflects the cutter's ability to design a beautiful polished gem, while still retaining as much of the original crystal's weight as possible. In many cases, naturals do not affect the clarity grade. In most cases, they are undetectable to the naked eye.

Another type of natural is the Indented Natural; in this case, the portion of the original rough diamond's surface which is left on the polished diamond dips slightly inward, creating an indentation. Usually, the cutter makes an effort to cut the polished diamond so that the indented natural will be confined to either the girdle or the pavilion (making it undetectable to the naked eye in the face-up position).

Needle:
A long, thin included crystal that looks like a tiny rod.

Nick:
A minor chip out of the surface of a fashioned diamond, usually caused by a light blow. It is more likely to be found along the girdle than elsewhere, although it may also appear on a facet junction or on a facet.

Nacre:
The iridescent substance secreted by a mollusk during the formation of a pearl that consists of layers of aragonite and calcite crystals.

Natural Pearl:
A pearl that originates naturally in a mollusk, as distinguished from cultured or imitation pearls.

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Q:

Quality:
Term used to describe the overall color, clarity and cut attributions of a stone.

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