Diamond Carat

Diamond Carat Weight:

Carat is often confused with the size of a diamond. But it is actually a measure of the weight of a diamond. One carat is equivalent to 200 milligrams. One carat can also be divided into 100 “points.” A .75 carat diamond is the same as 75 points, or a ¾ carat diamond.

Large Diamonds & Carat Weight:

Contrary to popular belief, a one-carat diamond does not cost twice as much as a 0.5 carat diamond.  The 1 carat diamond actually costs much more, assuming color, clarity and cut remain constant. Larger diamonds are found relatively infrequently in nature and are therefore more valuable.

The larger the diamond = more valuable = greater cost.

Misconceptions About Diamond Size:

Sometimes a larger diamond may appear more brilliant than a smaller one. This is because light must travel a greater distance through a larger diamond. The result is a prism effect that your eye registers as more brilliant and fire. Cut and mounting can also make a diamond appear larger or smaller than its actual weight.

Carat vs. Karat

Many people confuse diamond karat and carat.  Carat refers to the weight of a diamond while karat refers to the purity of gold (not the weight).  You may see a 1.0 carat diamond set in 18 karat gold, for example.  The following table provides an approximate guide to the size and weight of round brilliant cut diamonds of ideal proportions. This also gives you an approximation of diamond carats in mm.  Please note that cuts and weights will always vary due to many different factors. Find your diamond carat weight below.  

Diamond Size/Carat Sizing Chart:
Round Diamonds Round Diamonds
width (mm)width (inch)Weightwidth (mm)width (inch)Weight
1.0 mm.039 inch.005 carat4.8 mm .40 carat
1.2 mm .008 carat4.9 mm .43 carat
1.3 mm .01 carat5.0 mm.197 inch.47 carat
1.5 mm .015 carat5.2 mm.205 inch1/2 carat
1.7 mm .02 carat5.4 mm .60 carat
1.8 mm .025 carat5.5 mm .63 carat
2.0 mm.079 inch.03 carat5.6 mm .65 carat
2.1 mm .035 carat5.8 mm.228 inch3/4 carat
2.2 mm .04 carat6.0 mm.236 inch.80 carat
2.4 mm .05 carat6.2 mm .85 carat
2.5 mm .06 carat6.4 mm .95 carat
2.7 mm .07 carat6.5 mm.255 inch or 1/4 inch1.00 carat
2.8 mm .08 carat6.6 mm 1.10 carat
2.9 mm .09 carat6.8 mm 1.17 carat
3.0 mm.118 inch1/10 carat7.0 mm.276 inch1-1/4 carat
3.1 mm .11 carat7.2 mm 1.33 carat
3.2 mm.125 inch or 1/8 inch.12 carat7.4 mm.291 inch1-1/2 carat
3.3 mm .14 carat7.6 mm 1.60 carat
3.4 mm .15 carat7.8 mm.307 inch1.75 carat
3.5 mm .16 carat8.0 mm.315 inch1.90 carat
3.6 mm .17 carat8.2 mm323 inch2.00 carat
3.7 mm .18 carat8.4 mm 2.15 carat
3.8 mm.150 inch1/5 carat8.6 mm.338 inch2.25 carat
3.9 mm .22 carat8.8 mm.346 inch2.50 carat
4.0 mm.158 inch.23 carat9.0 mm.354 inch2.65 carat
4.1 mm.162 inch1/4 carat9.2 mm 2.85 carat
4.2 mm .30 carat9.4 mm.370 inch3.00 carat
4.4 mm.173 inch.33 carat9.6 mm 3.15 carat
4.5 mm .35 carat9.8 mm 3.35 carat
4.6 mm.181 inch1/3 carat10.0 mm.394 inch3-1/2 carat

Diamond Education Home | Color | Clarity | Cut | Carat | Gold | Platinum