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Diamond Price Calculator
Use this free diamond price calculator to estimate what a diamond is worth from the 4Cs — carat, cut, color, and clarity — plus its shape. It starts from an editable per-carat base price dated November 2026 and adjusts it for every grade you pick, so you can compare stones side by side before you buy or sell.
Default base price: $7,500 per carat for a 1.00 ct round, Excellent cut, G color, VS1 clarity stone, as of November 2026. There is no free live diamond price API, so this is a dated default — edit the field for the latest price.
| Base price per carat | $7,500.00 |
| Size adjustment (per-carat rate) | $7,500.00 |
| Cut adjustment (Excellent) | × 1.00 |
| Color adjustment (G) | × 1.00 |
| Clarity adjustment (VS1) | × 1.00 |
| Shape adjustment (Round) | × 1.00 |
| Estimated price | $7,500.00 |
The 4Cs at a glance
Carat is the weight, cut decides the sparkle, color runs from D (colorless) to K (faint yellow), and clarity grades how free the stone is of flaws.
Price vs carat weight
Estimated price from 0.25 to 3.00 carats at your cut, color, clarity, and shape. The curve bends upward because larger stones cost more per carat.
How it works
A diamond's price is not a single number from a price list — it is the result of four grades multiplied together. This calculator starts from a base price per carat and adjusts it for each of the 4Cs and the shape, then multiplies by the carat weight. Every adjustment is shown in the breakdown table, so you can see exactly which grade is driving the price.
The base price is $7,500 per carat for a 1.00 carat round stone with an Excellent cut, G color, and VS1 clarity, as of November 2026. That is the reference stone: every other combination is priced relative to it. There is no free live diamond price API, so this calculator never fetches a live price — the number in the field is always the one used, and you should replace it with a current quote from a jeweller or a published price list before relying on the result.
Carat weight affects the price twice. First, the total price grows with the weight — a 2 carat stone costs roughly twice a 1 carat stone of the same grades. Second, the price per carat itself rises with size, because large rough crystals are rarer. Stones under half a carat are priced at about 55% of the base per-carat rate, 0.5 to 0.99 carat at 80%, 1.00 to 1.49 at the full rate, 1.50 to 1.99 at 125%, 2.00 to 2.99 at 160%, and 3 carats and above at 210%.
Cut is the grade that most affects how a diamond looks. An Excellent cut returns the most light and sparkles the most, so it holds the full price. Very Good keeps 92%, Good 82%, and Fair only 68% — a poorly cut stone looks dull even if its color and clarity are fine, and the market prices it accordingly. Color runs from D, which is completely colorless, down to K, which shows a faint yellow tint. D costs 25% more than the G reference, while K costs 30% less. Clarity runs from FL (flawless) at 145% of the reference down to I1 (visibly included) at 45%. Shape is the last adjustment: round stones cost the most, because cutting them wastes the most rough crystal, while fancy shapes such as marquise and asscher keep more of the stone and sell for 20% or so less per carat at the same grades.
The chart plots the estimated price from 0.25 to 3.00 carats at the cut, color, clarity, and shape you selected. You can see the curve steepen as the stone gets bigger — that is the size factor at work, and it is the reason a 2 carat stone costs far more than twice a 1 carat stone.
Worked example
Take a 1.50 carat princess-cut diamond with a Very Good cut, H color, and VS2 clarity, using the default base price of $7,500 per carat. Enter those values and the calculator works like this.
Step 1: Size factor. A 1.50 carat stone is in the 1.50–1.99 range, so the per-carat rate is $7,500 × 1.25 = $9,375.
Step 2: Cut. Very Good is × 0.92, so $9,375 × 0.92 = $8,625 per carat.
Step 3: Color. H is × 0.92, so $8,625 × 0.92 = $7,935 per carat.
Step 4: Clarity. VS2 is × 0.90, so $7,935 × 0.90 = $7,141.50 per carat.
Step 5: Shape. Princess is × 0.88, so $7,141.50 × 0.88 = $6,284.52 per carat.
Step 6: Multiply by the weight: $6,284.52 × 1.50 = $9,426.78.
The tool shows the same result: an estimated price of $9,426.78. Change any one grade — say the color from H to F — and the price moves by that grade's factor, which makes it easy to see where the money is going and where a small compromise saves the most.
FAQ
What are the 4Cs of a diamond?
The 4Cs are carat, cut, color, and clarity. Carat is the weight — one carat equals 0.2 grams. Cut is how well the stone is shaped and polished, which decides how much it sparkles. Color runs from D (colorless) to Z (visibly yellow). Clarity grades how free the stone is of internal flaws and surface blemishes. Together, the 4Cs decide most of a diamond's price.
How much does a 1 carat diamond cost?
A 1 carat round diamond with an Excellent cut, G color, and VS1 clarity is roughly $7,500 at the November 2026 base price used by this calculator. The range is wide: the same weight can cost under $3,000 with a Fair cut, K color, and SI2 clarity, or over $15,000 with a D color and flawless clarity. Shape matters too — fancy shapes usually cost less per carat than round stones.
Why do round diamonds cost more than other shapes?
Round brilliant diamonds cost more per carat because cutting one wastes more of the rough stone — up to 60 percent of the original crystal is lost — and because demand for round stones is highest. Fancy shapes such as princess, cushion, and oval keep more of the rough and sell for roughly 10 to 20 percent less per carat at the same grade. An oval or cushion can therefore give you a larger-looking stone for the same budget.
Does diamond clarity affect the price a lot?
Yes, but only up to a point. A flawless stone costs roughly 45 percent more than a VS1 stone of the same weight, cut, and color, while an SI1 stone costs about 22 percent less. Below VS2, most buyers cannot see the difference with the naked eye, so many jewellers suggest VS2 or SI1 as the sweet spot: eye-clean in normal wear, without paying for perfection only a loupe can see.
Is this diamond price a live market price?
No. There is no free live diamond price API, so this calculator uses an editable base price per carat — $7,500 for a 1 carat round, Excellent cut, G color, VS1 clarity stone — dated November 2026. Diamond prices move with the market, so check a current quote from a jeweller or price list and update the base price field before relying on the result.