Carat0.5% on the one-carat: the first rise in fifteen months
RAPI rose 0.5% for 1-carat goods in August, its first gain since May 2025. The 0.30-carat added 2% and the 0.50-carat 2.5%. The 3-carat, steady for eighteen months, fell 0.4%.
§1Asking prices, not settled trades.
The one-carat polished index rose in August. The Rapaport Trade Diamond Index for 1-carat round D to H, IF to VS2 goods gained 0.5% across the month, which Rapaport describes as its first increase in fifteen months, following readings that were flat or negative going back to May 2025. The release was published in New York on 2 September at 08:21 UTC. Below it, the 0.30-carat index gained 2% and the 0.50-carat 2.5%, both continuing a rebound this desk has been tracking since July. RAPI measures asking prices, not settled trades: it is the average asking price of the cheapest tenth of round diamonds in each of the top twenty-five quality categories listed on Rapaport Trade, the marketplace formerly called RapNet, which carries more than $8 billion of daily listings.
§2The size that turned the other way.
The category that turned is the three-carat, and it turned the other way. It slipped 0.4% in August after what Rapaport calls a year and a half of steadiness. That matters against what this paper printed on 4 August, when July was reported here as the first month since March 2025 in which none of the four headline sizes fell. That condition lasted exactly one month. Compounded across the two months, the 0.30-carat is up 3.63%, the 0.50-carat 4.35%, the 1-carat 0.50% and the 3-carat down 0.20%, on this desk's arithmetic from Rapaport's own monthly figures. The spread between the best and worst size over two months is 4.55 percentage points, and it is the small goods that are carrying it.
The three-carat had been steady eighteen months. In August it slipped.
§3Supply cuts, not buyers arriving.
Rapaport attributes the recovery to supply, not to a return of demand: miners and manufacturers cut production, and the categories that fell hardest in 2025 rebounded as the imbalance closed. Trading picked up after the summer slowdown, round stones outperformed fancies, and Indian manufacturers shipped to the United States once the July confirmation of a 10% tariff rate on Indian goods removed an uncertainty this paper reported on 2 August. Business at the India International Jewellery Show in Mumbai is described as brisk. Antwerp and Israel were seasonally quiet, and Chinese demand was slow ahead of the September Jewellery and Gem World fair in Hong Kong.
One further reason is given for the 1 to 1.49-carat band specifically: falling inventory, and reports of consumers cooling on lab-grown stones.
§4What the release does not repair.
What has not been repaired sits in the same release. Rapaport notes miners still reporting sales declines, citing Alrosa's first-half revenue down 36% year on year to 74.16 billion roubles, or $901.6 million, with a loss of 10.67 billion roubles, and De Beers' first-half revenue down 19% to $1.58 billion. Both sets of figures were reported by this paper when they were published, on 6 August and 31 July respectively, and neither is new today.
Our own tape carries the RAPI 1.00-carat level at 3,881.34, a July 2026 point that is provisional and has not been revised since the last read, so it does not yet carry August's 0.5%. A monthly index is a monthly index, and this paper marks it as one rather than pretending it moves daily.
A half point is a small number and it is the right size for what happened. Fifteen months of the one-carat not rising is the fact that has organised every polished conversation since the middle of last year, and it has ended on supply discipline rather than on buyers arriving, which is the same engine that produced July.
A jeweller restocking for the holidays should read the 0.30 to 0.69 band as genuinely firmer and the three-carat as the size where the estimate book now needs checking, because eighteen months of steadiness ending is a change in a number that had stopped being watched. The test is the same one this desk named on 4 August and it is now days away: Vicenzaoro opens tomorrow and Hong Kong follows, and September is when the asking prices in this index meet budgets.
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