The Stone Index: Two-Thirds of the Top of the Market Weighs Five Carats or More

Two-thirds of the stones LEGACY catalogues weigh five carats or more, and above ten carats the shape buyers reach for changes. This is the first edition of The Stone Index — a standing count of what actually exists at the top of the market, drawn from our own recorded inventory rather than from estimates.

The finding

Of 6,420 catalogued stones with a recorded weight, 67.5% weigh five carats or more. Just 1.9% weigh under one carat. That distribution is the inverse of the diamond market as a whole, where sub-one-carat goods account for the overwhelming majority of stones cut and sold each year.

This is not a claim about taste. It is a description of a specific, narrow segment — the stones that reach a house dealing in rare goods — and it is worth recording precisely because that segment is almost never counted in public.

How the weight actually distributes

The single largest band is five to ten carats, at 28.5%. The striking figure is the last row: 17.6% of catalogued stones weigh twenty carats or more. In the wider market a twenty-carat stone is an event. Here it is roughly one in six.

The reason is selection, not abundance. A house that deals in rare goods sees the tail of the distribution, not its body. What the Index records is the shape of that tail — and the tail is where almost all of the world’s significant stones sit.

Shape inverts with size

Across the full catalogue, the ranking of shapes runs Round Brilliant, then Emerald Cut, then Pear Shape. Above ten carats, that order changes:

Emerald Cut leads Pear Shape by more than three hundred stones across the catalogue as a whole. Above ten carats the position reverses and Pear moves ahead. The preference order is not stable across weight.

There is a physical reason to expect this. The emerald cut is a step cut: broad open facets, a large flat table, and very little of the light-scattering that hides inclusions. As a stone grows, that openness becomes less forgiving — the table becomes a window onto the interior. Brilliant-family cuts, of which the pear is one, scatter light across many small facets and remain visually forgiving at size. At ten carats the difference stops being academic.

It is also true that a large pear reads as larger than its weight. Elongated outlines cover more finger, and at these weights presence is often the point.

Colour: what a stated grade actually looks like here

Of 4,835 stones carrying a stated colour, the distribution runs:

Two figures deserve attention. The first is 12.2% graded D — the top of the colourless scale, better than one in eight of the stones whose grade is recorded. The second is 22.9% fancy colour diamonds. The figure commonly cited in the trade is that roughly one natural diamond in ten thousand shows meaningful fancy colour. Against that reference point, the concentration recorded here is of a different order entirely — which is what one would expect of a selected inventory, and which is precisely the kind of statement that should be published with its denominator attached rather than asserted.

The K–M figure — six stones, 0.1% — is the most quietly informative number in the table. Warmer grades are not part of what gets catalogued here.

The rarity tail

Beyond the diamond colour scale sits a small group of stones counted in single figures across the entire catalogue: four Paraíba tourmalines, three Padparadscha sapphires, and one each of indicolite, mint green, seafoam and purple-grey.

These are not rounding errors. They are the stones for which no reliable market-wide count exists at all, because they surface too infrequently to be counted. Recording them, edition after edition, is the point of keeping an index rather than writing an article: the value accrues in the series, not in any single reading.

Methodology

This edition draws on 8,260 catalogued pieces held by LEGACY Diamonds & Gemstones as of 28 July 2026. Of those, 6,420 carry a recorded stone weight and 4,835 carry a stated colour; percentages are calculated against those stated sets, never against the full catalogue, and the denominator is given with every figure. Where a piece carries more than one stone, the principal stone governs. Weight bands are inclusive of the lower bound.

Two limits should be stated plainly. Clarity is recorded on hand for a minority of catalogued stones, and the certifying laboratory is named on a smaller set again. We have therefore published neither a clarity nor a certification distribution in this edition, because the recorded coverage does not yet support one. Both will be added when the underlying records justify it, and this note will be updated to say so.

No pricing information is included in the Index and none will be. The Index counts stones, not values.

The Stone Index is compiled by The Stone Market Desk and published under the masthead of The Record. Figures may be quoted with attribution to LEGACY — The Record. Journalists seeking the underlying breakdown may write to press@legacydiamondsandgemstones.com.

First edition. Last verified 28 July 2026.