Diamond education · Carat
Carat measures weight, not width. One carat equals 200 milligrams, but diamond prices do not rise in a straight line: larger gem-quality rough is rarer, and price per carat usually increases at popular milestone weights.
A quoted price per carat is multiplied by the stone’s weight, but that rate also changes with weight, shape, cut, color, clarity, origin and market supply. A two-carat diamond therefore usually costs more than twice as much as a comparable one-carat diamond. Natural and lab-grown diamonds also follow different price curves.
Demand clusters around familiar sizes such as 0.50, 1.00, 1.50 and 2.00 carats. Diamonds just below those marks may carry a lower rate while appearing nearly identical once set. The saving is not guaranteed—quality and exact dimensions still matter—but comparing 0.90–0.99 with 1.00 carat is a useful starting point.
Two stones with equal weight can have different length and width. A deep stone hides more weight below the girdle; elongated oval, pear and marquise shapes often cover more finger area. Do not chase spread at the expense of cut, because overly shallow proportions can reduce light return. Use the price curves to compare weights and the 3D builder to compare overall design proportions.
There is no single one-carat price. Origin, cut, color, clarity, shape, certification and the individual stone all change the amount. The calculator provides a range for selected specifications rather than a guaranteed quote.
Often the face-up difference is small, especially when the 0.90 carat stone is well proportioned. Compare millimeter measurements rather than assuming the label predicts appearance.
Elongated shapes such as marquise, oval and pear often provide greater visible coverage, while depth and outline proportions still influence the result.