What a carat actually looks like
A carat is a measure of weight, not size — 0.20 grams. Because weight rises with the cube of the diameter, doubling the carat does not come close to doubling how big a stone looks. Every diamond below is drawn to true scale on an average 17 mm ring finger.
The same carat, ten different sizes
Carat is weight, not size. Elongated cuts carry less of that weight hidden in the pavilion and spread wider across the finger, so they look considerably bigger than a round of identical weight — and cost the same or less.
| Shape | Length | Width | Against a round | What to know |
|---|
Dimensions assume well-cut stones of standard proportions. Individual stones vary, and two diamonds of the same shape and weight can differ by half a millimetre or more.
Carat to millimetre table
Face-up diameter for a well-cut round brilliant, with typical US retail and realistic resale for a G colour, VS2, Very Good cut natural stone.
| Carat | Diameter | Typical retail | Realistic resale |
|---|
Diameters assume standard proportions. A deep-cut stone of the same weight looks smaller face-up; a shallow one looks larger but loses brilliance. This is why two 1 carat diamonds can look noticeably different sizes.
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Get the retail range and the honest resale range for your exact stone.
Value my diamondPopular sizes and shapes
True millimetre size, retail price and the resale figure, for each carat and shape.