What is a 0.5 or 1 carat diamond worth when you sell it?

Why is diamond priced per carat?

With diamond, a carat is a weight: exactly 0.2 grams. The trade works with a price per carat, which you multiply by the weight of the stone. Half a carat is 0.50 carat, a whole one 1.00.

That price per carat is not the same for every weight. Larger stones are rarer, so a carat in one large stone costs more than a carat in two small ones. A 1 carat stone is therefore worth well over twice as much as a comparable half-carat stone.

The jumps at round weights

The price per carat does not rise gradually but jumps at round weights: half a carat, one, one and a half, two. A 0.99 carat stone and a 1.00 carat stone cannot be told apart by eye, yet the second sits in a higher price bracket.

That is why a buyer weighs to a hundredth of a carat. With a set stone, the weight is estimated from the diameter and depth; if the weight is on a report, that figure applies.

What decides the buying value of a 0.5 or 1 carat stone?

Besides weight, five characteristics count:

• Colour, from D (colourless) to Z (clearly tinted). Between two letters you see little difference by eye, but the price does.
• Clarity, from FL (no inclusions under magnification) to I3. Inclusions visible to the naked eye push the price down sharply.
• Cut: for round brilliants the cut grade from Excellent to Poor, and the shape. Round, princess, emerald and cushion each have their own price level.
• Fluorescence: strong blue fluorescence can mean a discount on colourless stones.
• The report: a report from GIA, HRD or IGI removes uncertainty. Without one, gemmologists assess the stone themselves.

Why the offer is lower than what you paid in the shop

The shop price of a diamond ring includes the jeweller’s margin, the work on the setting, advertising and VAT. When you sell, you receive the trade value of the loose stone: what a trader can pay for it at that moment. That gap is large with every piece of jewellery and has nothing to do with your stone.

We work with the trade prices per carat of an international diamond trading platform, for natural stones with the characteristics our gemmologists measure. Our diamond calculator shows you in advance the order of magnitude of your stone; the final offer follows after measurement.