1 Carat Round Diamonds

One carat is the number most people arrive with, and the round brilliant is the shape they usually picture. Together they are the single most searched combination in the category — and the most expensive way to buy that weight, because demand concentrates exactly here.

The stones on this page run from 0.90 to 1.09 ct. That range is deliberate. A 0.95 ct round measures about 6.3 mm across, a 1.00 ct about 6.5 mm: the difference is roughly the width of a human hair, invisible on the hand, and it can cut the price by ten percent or more. If your budget is fixed, buying just under the round number is the easiest saving in diamonds.

Spend what you save on cut. In a round brilliant the cut grade governs how much light comes back, and an Excellent cut in colour H outperforms a Good cut in colour E every time. Aim for Excellent cut, colour G to I, clarity VS2 or SI1 — at one carat, SI1 inclusions in a round are almost always invisible without a loupe.