CARAT WEIGHT
Carat is often confused with the size of a diamond, but 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 a 75 points, or a ¾ carat diamond.
Larger diamonds are found relatively infrequently in nature and are therefore more valuable. Because of this, a 1-carat diamond will NOT cost exactly twice the price of a ½ carat diamond. It will cost much more than this, assuming color, clarity and cut remain constant.
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.
Many people confuse carat and karat. Carat refers to the weight of a diamond while karat refers to the purity of gold (not the weight). You may see a 1 carat diamond set in 18 karat gold, for example.
The following table provides an approximate guide to the relative size in millimeters, inches and weight of round brilliant cut diamonds of ideal proportions. Please note that cuts and weights will vary due to many factors.
| Round Diamonds |
|
Round Diamonds |
| width (mm) |
width (inch) |
Weight |
width (mm) |
width (inch) |
Weight |
| 1.0 mm |
.039 inch |
.005 carat |
4.8 mm |
|
.40 carat |
| 1.2 mm |
|
.008 carat |
4.9 mm |
|
.43 carat |
| 1.3 mm |
|
.01 carat |
5.0 mm |
.197 inch |
.47 carat |
| 1.5 mm |
|
.015 carat |
5.2 mm |
.205 inch |
1/2 carat |
| 1.7 mm |
|
.02 carat |
5.4 mm |
|
.60 carat |
| 1.8 mm |
|
.025 carat |
5.5 mm |
|
.63 carat |
| 2.0 mm |
.079 inch |
.03 carat |
5.6 mm |
|
.65 carat |
| 2.1 mm |
|
.035 carat |
5.8 mm |
.228 inch |
3/4 carat |
| 2.2 mm |
|
.04 carat |
6.0 mm |
.236 inch |
.80 carat |
| 2.4 mm |
|
.05 carat |
6.2 mm |
|
.85 carat |
| 2.5 mm |
|
.06 carat |
6.4 mm |
|
.95 carat |
| 2.7 mm |
|
.07 carat |
6.5 mm |
.255 inch
or 1/4 inch |
1.00 carat |
| 2.8 mm |
|
.08 carat |
6.6 mm |
|
1.10 carat |
| 2.9 mm |
|
.09 carat |
6.8 mm |
|
1.17 carat |
| 3.0 mm |
.118 inch |
1/10 carat |
7.0 mm |
.276 inch |
1-1/4 carat |
| 3.1 mm |
|
.11 carat |
7.2 mm |
|
1.33 carat |
| 3.2 mm |
.125 inch
or 1/8 inch |
.12 carat |
7.4 mm |
.291 inch |
1-1/2 carat |
| 3.3 mm |
|
.14 carat |
7.6 mm |
|
1.60 carat |
| 3.4 mm |
|
.15 carat |
7.8 mm |
.307 inch |
1.75 carat |
| 3.5 mm |
|
.16 carat |
8.0 mm |
.315 inch |
1.90 carat |
| 3.6 mm |
|
.17 carat |
8.2 mm |
323 inch |
2.00 carat |
| 3.7 mm |
|
.18 carat |
8.4 mm |
|
2.15 carat |
| 3.8 mm |
.150 inch |
1/5 carat |
8.6 mm |
.338 inch |
2.25 carat |
| 3.9 mm |
|
.22 carat |
8.8 mm |
.346 inch |
2.50 carat |
| 4.0 mm |
.158 inch |
.23 carat |
9.0 mm |
.354 inch |
2.65 carat |
| 4.1 mm |
.162 inch |
1/4 carat |
9.2 mm |
|
2.85 carat |
| 4.2 mm |
|
.30 carat |
9.4 mm |
.370 inch |
3.00 carat |
| 4.4 mm |
.173 inch |
.33 carat |
9.6 mm |
|
3.15 carat |
| 4.5 mm |
|
.35 carat |
9.8 mm |
|
3.35 carat |
| 4.6 mm |
.181 inch |
1/3 carat |
10.0 mm |
.394 inch |
3-1/2 carat |