IGI GEMOLOGICAL EDUCATION

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Diamond weight is expressed in carats. 1.00 carat equals 200 milligrams. Diamonds under 1.00 carat are expressed in ‘points.’ That means a 0.90 carat diamond is said to weigh "90 points." You should know that two diamonds which weigh the same don’t always look the same size. To see examples, click above and “Learn With Videos.” You may also consult your jewelry professional, or contact us directly at igi.org.

A diamond’s color is caused by chemicals in the earth where the diamond formed. The most common color is yellow, and most diamonds are graded on a scale ranging from D, which is most colorless, to Z, which is light yellow or brown. To see examples, click above and “Learn With Videos.” You may also consult your jewelry professional, or contact us directly at igi.org.

Clarity evaluates a gemstone’s internal and external clarity-characteristics. Internal characteristics are classified as inclusions. External characteristics are classified as blemishes. A gemologist analyzes clarity by looking down through the top of the stone at 10-power magnification. To see examples, click above and “Learn With Videos.” You may also consult your jewelry professional, or contact us directly at igi.org.

The cut of a diamond refers to everything man has done to convert it from a rough diamond crystal into a finished gemstone capable of producing brightness, fire and scintillation. More than any other “C” the way a diamond is cut determines how big, bright and lively it appears. To see examples, click above and “Learn With Videos.” You may also consult your jewelry professional, or contact us directly at igi.org.