Diamond's Carat Weight

Diamond's Carat Weight

Diamond Carat Weight A carat (ct.) is the unit of measurement specifically used to describe the weight of a diamond (or other gemstones). Its name comes from the carob seed – a small seed with a typically uniform weight that early gem traders used as counterweights for balancing their scales, according to the GIA. A single carat is equivalent to 0.2 grams, or 200 milligrams, and is divided into 100 points.AA certified diamond that comes with a grading report will indicate the exact carat weight to the nearest hundredth of a carat, in decimal format. A 1-carat diamond has 100 points (1.00) while a ¾ carat stone has 75 points (0.75). Carat weight in pre-set jewelry is typically described as a fraction (e.g. ¾ carats) and has an equivalent decimal range (¾ carats = 0.69 – 0.82 points). The following table correlates fractional sizes with their decimal equivalent:


Diamonds size chart:

Diamonds in weight
No Carat Size Image Weight
1 0.01 2 milligram = 0.002 gram
2 0.03 6 milligram = 0.006 gram
3 0.05 10 milligram = 0.010 gram
4 0.07 14 milligram = 0.014 gram
5 0.10 20 milligram = 0.02 gram
4 0.15 30 milligram = 0.03 gram
7 0.20 40 milligram = 0.04 gram
8 0.25 50 milligram = 0.05 gram
9 0.33 66 milligram = 0.06 gram
10 0.40 80 milligram = 0.08 gram
11 0.50 100 milligram = 0.10 gram
12 0.65 130 milligram = 0.013 gram
13 0.75 150 milligram = 0.015 gram
14 0.85 170 milligram = 0.017 gram
15 1.00 200 milligram = 0.020 gram
16 1.25 250 milligram = 0.025 gram
17 1.50 300 milligram = 0.030 gram
18 1.75 350 milligram = 0.035 gram
19 2.00 400 milligram = 0.040 gram
20 2.25 450 milligram = 0.045 gram
21 2.50 500 milligram = 0.050 gram
22 3.00 600 milligram = 0.060 gram
23 4.00 800 milligram = 0.080 gram
24 5.00 1000 milligram = 1 gram
25 6.00 1200 milligram = 1.2 gram
26 7.00 1400 milligram = 1.4 gram
27 8.00 1600 milligram = 1.6 gram
28 10.00 2000 milligram = 2.0 gram
29 15.00 3000 milligram = 3 gram
30 20.00 4000 milligram = 4 gram

The carat is probably the most familiar of the 4C terms because it is the easiest one to understand just by looking at the stone. However, people often mistakenly assume that a diamond’s size is synonymous with its weight, though that’s not necessarily true. The way a diamond is cut can actually obscure its size and true weight. The following diagram shows the relative size of carat weights for a diamond that is cut to the same proportions:Note: Diamond illustrations show relative size, not actual size.