Good for carat, colour, clarity and cut filters
Blue Nile round diamonds
See rounds on Blue NileOpens Blue Nile's site. Not a referral link.
Guide: carat weight
Carat weight and price
Twice the weight costs far more than twice the price for a natural diamond, and buyers pay extra for round numbers.
- $2,160/ct
- Natural, 0.90 to 0.99 ct (median)
- $3,419/ct
- Natural, 1.00 to 1.09 ct (median)
Brilliant Earth listings, read Oct 2, 2026. See source
On this page
Price per carat, explained
A carat is a unit of weight: 200 milligrams, and a "point" is one hundredth of a carat3. Price per carat is the listing price divided by the weight. If price grew in step with weight, price per carat would stay flat. It does not.
Median price per carat by weight band, Brilliant Earth, October 2, 2026
| Weight band | Natural (listings read) | Laboratory-grown (listings read) |
|---|---|---|
| 0.70 to 0.89 ct1 | $1,959 (22) | $745 (6) |
| 0.90 to 0.99 ct1 | $2,160 (10) | $760 (3) |
| 1.00 to 1.09 ct1 | $3,419 (130) | $738 (21) |
| 1.40 to 1.49 ct1 | $3,968 (6) | $689 (5) |
| 1.50 to 1.59 ct1 | $5,259 (50) | $960 (27) |
| 2.00 to 2.09 ct1 | $6,923 (98) | $1,252 (117) |
| 3.00 to 3.09 ct2 | $10,073 (13) | $1,472 (73) |
| Source | Brilliant Earth naturalRead Oct 2, 2026 | Brilliant Earth lab grownRead Oct 2, 2026 |
All seven shapes we read (round, oval, emerald, cushion, pear, princess, radiant), all colour and clarity grades mixed. Bands with few listings are rough. Medians are computed from the listings we read on October 2, 2026 (the first ~100 listings of each merchant page in its default order, all colour and clarity grades mixed). They show the spread on that page that morning, not a market average.
What the steps mean for a budget
The 1 carat step. Natural stones between 0.90 and 0.99 carats had a median of about $2,160 per carat; from 1.00 to 1.09 carats it was about $3,4191. Part of that is grade mix, but the pattern matches the common advice to look just under a round number. A 0.95 carat stone looks almost the same once set.
The 1.5 carat step. Again natural: about $3,968 per carat from 1.40 to 1.49 carats and $5,259 from 1.50 to 1.591.
Laboratory-grown stones barely step. Price per carat stayed between about $690 and $960 from 0.7 to 1.59 carats12. The round-number premium is small, so the "just under" trick saves little.
Total weight is not centre weight. A ring described as "1 ct. tw." adds up every stone. Compare the centre stone's own weight.
How jewelers must state weight
Under the FTC Jewelry Guides, a decimal weight must be accurate to the last decimal place shown: a stone listed at 1.50 carats must weigh 1.50 carats to two decimals3.
Weights stated as fractions ("1/2 ct", "3/4 ct tw") are allowed only with a conspicuous disclosure that the weight is not exact and of the range or tolerance used for each fraction3. If a ring page shows a fraction, look for that disclosure and the range.
The same Guides say terms such as "properly cut" or "modern cut" may not describe a stone that is lopsided or so deep or shallow that brilliance suffers4. Ask for the proportions on the report, not just the cut name.
Round diamond listing pages
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Good for filtering just under 1.00 and 1.50 carats
Brilliant Earth round diamonds
See rounds on Brilliant EarthOpens Brilliant Earth's site. Not a referral link.
Also on Brilliant Earth's site
About this page
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Diamond listings change by the hour: stones sell, prices move and sales start and end. Every price here is the merchant's listed price on the date shown. The merchant's own page is the final word on price, availability and terms.
RingPrice Index does not sell jewelry, does not grade stones and does not take your details. We read merchants' public listing pages and report what they showed.
