Diamond price per carat.

Answer

Total price = price per carat x carat weight, and price per carat = total price / carat weight. A 1 carat stone at $6,000 per carat costs $6,000. A 3/4 carat (0.75 ct) stone at $3,600 total is $4,800 per carat.

Worked example

Stone A: 1 ct at $6,000 per carat = $6,000 total. Stone B: 0.75 ct for $3,600 total = 3,600 / 0.75 = $4,800 per carat, which is $1,200 per carat (20.0%) below A. B weighs 150 mg against 200 mg for A. Prices here are examples, not market quotes.

How it works

Per carat = total / carats. Total = per carat x carats. Per 0.01 ct = per carat / 100. The metric carat is 200 mg, so mg = carats x 200. A fraction such as 3/4 or 1 1/2 is converted to a decimal. Per-carat price is a comparison tool only: it is not a valuation, because cut, colour, clarity and certification set what a stone is worth.

Sources and basis (opened 2026-10-08): Wikipedia, Carat (mass).

FAQ

How do I calculate the price of a diamond from the price per carat?

Multiply the price per carat by the carat weight. At $5,000 per carat, a 1.2 ct stone is $6,000.

How do I find the price per carat from a total price?

Divide the total price by the carat weight. A $3,600 stone of 0.75 ct is $4,800 per carat.

How many milligrams is a carat?

One metric carat is 200 milligrams.

Why do two diamonds with the same carat weight cost different amounts?

Cut, colour, clarity and certification all affect price. This calculator compares the numbers you enter and does not value a stone.

Can I type 3/4 instead of 0.75?

Yes. Fractions like 3/4 and 1 1/2 are accepted for carat weight.