Glossary of Diamond Terms

EGL - European Gemological Laboratory: A franchise diamond grading facility.

Eye-clean - a clarity grading term for diamonds that have no inclusions visible to the unaided eye.

Extra Facet - a facet added to a diamond in addition to the required facets for a particular cutting style.

Facet - the flat, polished surfaces on a diamond.

Feather - a fracture within a diamond that resembles a feather.

Fire - the separation of white light into the spectral colors due to differences in the refraction of the various wavelengths. Also known as dispersion.

Finish - general category describing the aspects of polish and symmetry.

Fluorescence - a glow, usually of a bluish color, but sometimes in white, yellow, or yellow/orange hues, which emanates from certain diamonds when exposed to ultraviolet light.

Fracture - irregular step-like or splintery breaks in a diamond along a direction other than a cleavage plane.

Fracture Filling - an artificial clarity enhancement process in which an inclusion is injected with filler material to mask its presence.

GIA - Gemological Institute of America: a nonprofit institution established in 1931 to serve educational needs of the jewelry industry.

Girdle - the setting edge around the width of a diamond.

HRD - Hoge Raad voor Diamont (Diamond High Council) a nonprofit organization of the Belgian diamond industry, founded in 1973.

Hearts & Arrows - a trade name for the optical phenomenon observed within a diamond utilizing filtered light whereby "hearts" and "arrows" can be seen in the crown and pavilion.

Ideal Cut - "Ideal" also known as the "American Ideal Cut", a cutting style that is based on the Tolkowsky theoretical brilliant cut diamond.

IGI - International Gemological Institute - Provides diamond and colored stone grading reports and appraisals. Offices located in New York, Antwerp, and Thailand.

Included Crystal - a mineral crystal contained in a diamond.

Indented Natural - a natural that penetrates the stone.

Internal Graining - internal indications of irregular crystal growth; can appear as faint lines, streaks, or have a milky appearance.

Inclusion - any of several types of clarity characteristics, which are found internally within the gemstone.

Knot - an included diamond crystal that reaches the surface of a finished stone.

Laser Drilling - an artificial clarity enhancement process in which a laser is used to drill to an inclusion within a diamond which is then bleached to appear white.

Laser Inscription - a technique to hallmark, brand or inscribe the edge of a diamond with a serial number or other inscription.