A GLOSSARY OF DIAMOND RELATED TERMS
Blemish Blemishes are the external identifying characteristics of a diamond used to help determine the gem’s clarity.
Brilliance Flashes of white light refracted through a diamond.
Carat(ct.) Is the international standard for measuring the weight of gemstones. When referring to a diamond smaller than one carat, jewelers usually talk in terms of points, i.e.,one-half a carat is often referred to as 50 points.
Cut Cut consists of two vital parts. 1.Outline shape and style of the gemstone; pear, marquise, princess, etc. 2. Proportions, often referred to as “make”. Relates to how effectively the diamond is cut and polished to produce maximum beauty.
Certification Often referred to as a “cert”. A document created by an independent laboratory to identify characteristics of a diamond at a certain point in time. At GIA, it is called a diamond grading report.
Color While diamonds come in all colors, most people think of diamonds as white. Diamonds in today’s market range from colorless to light yellow. A colorless diamond is more rare than one with a little color.
Color treatment There are several methods of enhancing the color of a diamond. These include irradiation, annealing, and a relatively new method referred to as HTHP (high temperature high pressure). Both annealing and irradiation treatment may be damaged during normal jewelry repair procedures. HTHP treatment so far appears to be permanent.
Clarity A diamond’s clarity is determined by the type, number, size, location, and relief of the unique internal and external characteristics of the gemstone. Imagine it as the gem’s fingerprint; just like the human fingerprint no two are alike. Your diamond will be as unique as you are.
Culet The facet at the very bottom tip of the diamond. It is generally not visible and some stones don’t have one.
Crown The area above the girdle on a polished diamond.
Dispersion White light inside a diamond separated into spectral hues (red, orange, yellow, green, blue, and violet). You see it as tiny flashes of color in a well-cut diamond. Often referred to as fire in a diamond.
Facet The flat, polished surface on a finished diamond. A round brilliant cut diamond has approximately 58 facets.
Fluorescence Some diamonds emit visible light (blue, yellow, green, etc.) only when exposed to an ultraviolet light source, i.e., a black light at a disco. If the fluorescence is strong it may have a negative effect on value.
Fracture filling Some diamonds have surface reaching feathers (fractures) which are naturally occurring. Sometimes a transparent molten glass-like composite is pressure filled into the fractures thereby making them less visible. This clarity treatment is not stable and subsequently not permanent. It can be damaged with normal cleaning and repair procedures.
GIA The Gemological Institute of America. An independent not-for-profit entity whose mission is education and laboratory services to serve the jewelry industry and to secure the public trust.
Girdle The narrow edge of the circumference on the diamond. It can vary from extremely thick to very thin.
Inclusion Inclusions are the internal identifying characteristics of a diamond used to help determine the gem’s clarity.
Karat gold Pure gold is too soft therefore, it’s mixed (alloyed) with other metals and it’s this alloying that makes karat gold. This improves the durability, as well as, allows for the various colors of gold available like white, rose, and green gold. The karat is based upon the number of parts per thousand of gold and its constituent alloys, i.e., 18K gold is 750 parts pure gold and 250 parts other metals, like silver and copper.
Laser drilling A diamond clarity treatment process for diamonds with dark inclusions. A laser drills into the diamond and vaporizes the dark inclusion. If it doesn’t vaporize, then a bleaching process is applied to lighten the diamond inclusion or acid is applied to dissolve it. However, instead of one inclusion, you now have two—the area of the original inclusion and the laser drill-hole.
Pavilion The area below the girdle on a polished diamond.
Platinum and its alloys Often referred to as the platinum group of metals (PGM), which include platinum, iridium, palladium, ruthenium, rhodium, and osmium. Not all are used for jewelry. Pure platinum like pure gold is generally too soft for durable jewelry, so it is alloyed with up to 10 percent iridium, or ruthenium or cobalt to increase its strength.
Point A point is 1/100th of a carat. Think of it just like the decimal system. A carat diamond is 1.00 carat.
Scintillation Flashes of light reflected from a polished diamond as the result of movement.
Table Broad flat surface, the largest facet on a diamond. It is the shape of a stop sign on a round brilliant cut diamond.
The 4C’s A diamond’s cut, color, clarity, and carat weight, which in combination determine the value of the diamond.
Total weight When there is more than one gemstone in a piece of jewelry, often the item’s gem weights are discussed in terms o