The carat of a diamond 4 C's of diamonds Glossary of terms Jewelry cutting diamond ~ 1Earth Antiques and Appraisals Magazine

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CARAT

A diamond's weight is measured in carats, with one carat being equivalent to 100 points. You will often see a diamond referred to as a 3/4-carat stone or a 75-point diamond. Larger stones are often more highly valued, but size should not be the only consideration--high brilliance, which varies according to clarity, cut, and color grade, is highly desirable in a diamond.

A carat is divided into 100 points so:

1/4 ct. = 25 points = .25 ct.
1/3 ct. = 33 points = .33 ct.
1/2 ct. = 50 points = .50 ct.
3/4 ct. = 75 points = .75 ct.

The first diamonds were discovered in India about 500 B.C. The carob seed was first unit of weight to weigh diamonds; with a 1.00 ct. diamond weighing the same as a seed from the seed pod of the carob or locust tree.

Today the metric system is used to weigh diamonds with the carat as the unit of diamond weight. To give an accurate measurement sophisticated equipment like the electronic balance, screw micrometer, the Moh gauge and the Leverage gauge are used.

1 metric carat = 0.2 grams
1 metric carat = 200 milligrams
1 metric carat = 1/142 ounce

Do not confuse carat with karat. Carat refers to stone weight while karat refers to fineness of gold.

Diamonds that weigh less than .01 ct. (1 point) to greater than 100 carats for jewelry. The diamonds that weigh less than 1/5 ct. (20 points) are called melee. These melee can be full cut (with 57 or 58 facets) or single cut (17 or 18 facets)

The price per carat increases as a diamond's weight increases. Larger diamonds are more rare and when these larger diamonds also have higher color, clarity and cut grades the value or price per carat increases greatly. The rarer the diamond, the more expensive.

WEIGHT RETENTION

A diamond may have extra or unnecessary weight. This is weight that does not enhance the fineness or appearance of largeness. This is caused by a girdle that is too thick. For example, consider two different stones with exactly the same grades and dimensions with exception of girdle thickness. When these diamonds are mounted they look nearly identical. The one with the thick girdle weighs more, so it will be more expensive. However, it's only heavier, not nicer.