Your Ultimate Guide to Understanding Diamond Carat and Size
Carat is one of the most important of the four C's of diamond buying: It's the globally recognized standard for the weight of a diamond (not to be confused with karat, a measure of gold purity). Although we’re sure you’ll have many brides-to-be argue that it’s the most important of the aspects since it has such a big impact on the look of your engagement ring. You'll hear a lot about it while you're shopping for your engagement ring, so here are the most important things to know, including how much a carat weighs and how it's priced. To get a quick understanding on Diamond Carat, watch our co-founder Anubh discuss this topic below.
How much does a diamond carat weigh?
A 1 carat (or ct) diamond weighs 0.20 grams. Contrary to popular belief, the carat is not the size of the diamond. A diamond's size is measured in millimeters, length by width — in other words, the diameter of the diamond. It typically takes about 250 tons of rock mining to produce a single 1 carat diamond. That's why diamonds are rare and expensive.
Diamonds come in a variety of shapes and carat weights. A diamond cutter’s highest priority is to maximize carat weight. The larger the diamond, the rarer and therefore more expensive it is. Diamonds are weighed very precisely, to the nearest 0.01ct.
Before universal adoption of the carat in 1907, a variety of measurements were used for diamonds. (At one point carob seeds were used, because it was believed — incorrectly — that the mass of each seed didn't vary much.) Over time, carat weight became standardized. It's now a common point of reference on the certificate of any diamond, regardless of which institution certifies it.
Diamond MM Chart
Carat price effect: What does a diamond carat cost?
Diamond pricing increases exponentially — not linearly — as diamond carat weight increases. That means once a diamond hits it’s critical weight, the price bumps up. The critical weights are 0.30ct, 0.40ct, 0.50ct, 0.70ct, 0.90ct 1.00ct, 1.50ct, 2.00ct, 3.00ct, 4.00ct, 5.00ct and 10.00ct.
Diamond cutters will do everything they can to keep the diamond weight at or above each critical weight. Diamond manufacturers and suppliers also know this trick, so they’ll price their diamonds accordingly. It might be smart to buy a 0.95ct diamond instead of 1 carat, but the former option is difficult to find. (Luckily, here at With Clarity, you have our team of expert gemologists to help you track down just the right stone in the right carat size.)
Carat price for lab grown diamonds
When purchasing within the same budget, try looking at lab diamond comparisons. Lab grown diamonds have the same physical, chemical, and optical properties as a natural diamond. The only stark difference is where they were created (earth vs laboratory). Refer to our table below to see price comparisons of round natural and lab diamonds. View certified lab diamond catalog.
Diamond Carat and Price
Natural Diamonds vs Lab Diamonds (based off round shapes).
Carat Size |
0.25 |
0.50 |
0.75 |
1.00 |
1.25 |
1.50 |
2.00 |
2.50 |
3.00 |
3.50 |
4.00 |
4.50 |
5.00 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Natural Diamond Price | $480 | $2,360 | $3,030 | $10,010 | $8,210 | $13,470 | $23,850 | $33,200 | $75,360 | $62,660 | $102,790 | $117,130 | $151,770 |
| Lab Diamond Price | $120 | $510 | $1,100 | $1,550 | $2,360 | $3,080 | $5,800 | $7,105 | $10,660 | $15,720 | $24,940 | $31,650 | $36,630 |
Values are estimated and can vary based on our inventory.