Carat is the standard unit of weight for diamonds and other gemstones. One carat equals one fifth of a gram. When weighing less than one carat, the diamond’s weight is expressed in “points”: each carat is divided into 100 points, for example: 0,75 carat = 75 points. 0,5 carat = 50 points. When diamonds are mined, large gems are discovered much less frequently than smaller ones. Diamond prices increase exponentially with carat weight. So, a 2-carat diamond of a given quality is always worth more than two 1-carat diamonds of the same quality.
Most gem quality diamonds used in jewelry are colorless and nearly colorless, sometimes with tints of yellow or brown. Among the rarest are the colors D, E and F on a scale that goes to Z.
Color grades are established by comparing each diamond to a set of master comparison diamonds. Each grade represents a range of color. Grading color is done in a specific and controlled lighting environment and according to strict color grading procedures. More color intensity than Z is called “fancy” color. Diamonds of all colors can be found in nature: over 300 colors have so far been identified, however these come in an infinite number of shades and hues.
Since diamonds form under tremendous heat and pressure, internal and external characteristics are common. These characteristics help gemologists separate natural diamonds from synthetics and simulants, and identify individual stones.
There are two types of clarity characteristics: inclusions and blemishes. The difference is based on their locations: inclusions are inside the diamond while blemishes are only on its surface.
Cut refers to the finish and proportions, and how these factors influence the overall appearance of a diamond. White and contrasted light called “brilliance”, the color flashes called “fire”, and “scintillation” or flashes of light that occur when the stone moves, the ratio of weight vs. size, the smoothness and symmetry of polished faces: all these determine how light enters the stone, in what way it returns to the eye, and how the stone performs in terms of sparkle. The Cut grade is expressed on a scale from Excellent to Poor.
Types of Diamond Certificates
A certificate is a “schematic plan” of a diamond. It reveals the diamond’s exact measurements and weight, as well as the details of its cut and quality. It describes the precise characteristics of the diamond. Certificates also serve as proof of the diamond’s identity and value.
Belgium Diamonds offers diamonds certified by HRD – Hoge Raad voor Diamant or Diamond High Council, GIA – the Gemological Institute of America, IGI – International Gemological Institute.
The Diamond High Council is the officially recognized representative of the Belgium diamond trade and industry. HRD headquarters are located in Antwerp, World Diamond Center.
The HRD diamond certificate, which guarantees the authenticity of a diamond and thus rules out the possibility of it being an imitation or a synthetic diamond. Also, the certificate contains a complete quality description of the diamond, with regard to shape, weight, clarity grade, fluorescence, colour grade, measurements, proportions and finish grade. These quality characteristics determine the value of the stone.
Established in 1931, the nonprofit Gemological Institute of America (GIA) is considered by many to be world’s foremost authority in gemology. GIA’s mission is to ensure the public trust in gems and jewelry by upholding the highest standards of integrity, academics, science, and professionalism through education, research, laboratory services, and instrument development.
The International Gemmological Institute is the oldest institute of its kind in Antwerp. Set up in 1975 with labs in New York, Bangkok, Mumbai and Tokyo .
The IGl Diamond Report is essentially a statement attesting to the authenticity of a diamond and providing a reliable and accurate statement of its identity and grade based on an internationally recognized system.
Each diamond is scientifically analyzed by several gemologists who use their experience in combination with state-of-the-art equipment to produce an accurate description of the characteristics of the diamond and the quality of its cut. With its detailed information presented in understandable language, the different qualities of a diamond can be truly appreciated.