When Jewelers refer to a diamond’s carat they are actually referring to the weight of the stone, not the size. In jewelry, the size of stones is measured in millimeters; since diamonds can be cut shallow, deep or ideally, it is impossible to accurately convert a diamond’s carat weight into an exact mm size. However, a very rough conversion can be made. Despite the ability to very roughly convert carat weight to size, the only accurate way to know the true carat weight of your diamond is to weigh it. Thus, 1 carat has become universally known as being a metric weight of 0.02 grams. The weight of a diamond has the most significant impact on its price. Since the larger a stone is, the rarer it is, one 2 carat diamond will be more expensive than the total cost of two 1 carat diamonds of the same quality. The carat of a diamond is often very important to people when shopping but it is a mistake to sacrifice too much quality for sheer size.

You may also hear jewelers refer to a diamond’s carat weight as a number of “points.” One carat equals 100 points. See below a generally accepted point conversion to fractions of a carat.

Acceptable Diamond Conversions

1/10 Carat= 9 points -12 points
1/7 Carat= 13 points -17 points
1/5 Carat= 18 points – 22 points
1/4 Carat= 23 points - 29 points
1/3 Carat= 30 points - 36 points
3/8 Carat= 37 points – 46 points
1/2 Carat= 47 points – 56 points
5/8 Carat= 57 points – 68 points
3/4 Carat= 69 points - 81 points
7/8 Carat= 82 points - 94 points
1 Carat= 95 points - 110 points