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.

F:

Facet:
The smooth, flat faces on the surface of a diamond. They allow light to both enter a diamond and reflect off its surface at different angles, creating the wonderful play of color and light for which diamonds are famous. The table below shows all the facets on a round brilliant cut diamond. A round brilliant 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.

Fancy Shape:
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.

Feathers:
These are small fractures in a diamond. They are usually caused by the tremendous stress that the diamond suffered while it was growing underground. 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. When viewed under magnification, some feathers are transparent and others have a light white appearance to them. 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" may sound scary, the reality is that, with normal wear and care, most feathers pose no risk to the diamond's stability. Consider this: even with the feathers, these diamonds 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 term refers to the qualities imparted to a diamond by the skill of the diamond cutter. The term "finish" covers every aspect of a diamond's appearance that is not a result of the diamond's inherent nature when it comes out of the ground. The execution of the diamond's design, the precision of its cutting details, and the quality of its polish are all a consideration when a gemologist is grading finish. If you examine a diamond's grading report, you will see its finish graded according to two separate categories: polish and symmetry.

Fire:
Often a term used instead of dispersion, it is the variety and intensity of rainbow colors seen when light is reflected from a diamond.

Fluorescence:
An effect that is seen in some gem-quality diamonds when they are exposed to long-wave ultraviolet light (such as the lighting frequently seen in dance clubs). Under most lighting conditions, this fluorescence is not detectable to the eye. However, if a diamond is naturally fluorescent, it will emit a soft colored glow when held under an ultraviolet lamp or "black light." Fluorescence is not dangerous to the diamond or to the wearer; it is a unique and fascinating quality that occurs naturally in a number of gems and minerals.

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.

Face:
A term used in brillianteering for the entire group of facets that can be placed won a diamond without reposition it in the dop; vis., two star facets and four upper-break facets or four lower-break facets. In crystallography, a natural, plane surface on a crystal.

Faceting:
The operation of placing facets on a diamond or other gem.

Fancy Diamond:
Any diamond with a natural body color strong enough to be attractive, rather than off color. 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.

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

Fissure:

An elongated cavity in a diamond’s surface. It may or may not have occurred along the line where a cleavage reached the surface.

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

Flaw:
Any external or internal imperfection on a fashioned diamond; e.g., a feather, fissure, carbon spot, knot, etc. Some diamond men limit its use to internal faults only, using the term blemish for surface faults. The terms flaw and imperfection are usually used interchangeably.

Flawless:
The recommended term for a diamond without external or internal flaws or blemishes of any description when viewed by a trained eye under efficient illumination and under a corrected magnifier of not less than ten power; binocular magnification under dark-field illumination is preferred. 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.

The recommended term for a diamond without external or internal flaws or blemishes of any description when viewed by a trained eye under efficient illumination and under a corrected magnifier of not less than ten power; binocular magnification under dark-field illumination is preferred. 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.

Four C’s:
A phrase coined for advertising purposes that sums up the numerous factors affecting diamond value into four categories: color, clarity, cutting, and carat weight.

Fracture:
The breaking or chipping of a stone along a direction other than a cleavage plane.

Full-cut Brilliant:
A brilliant-cut diamond or colored stone with the usual total of 58 facets, consisting of 32 facets and a table above the girdle and 24 facets and culet below.

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