Rapaport announced from New York on 2 September that its 1-carat diamond price index rose 0.5% in August, the first monthly gain for that size in fifteen months. It follows July, reported on 4 August, when the same index was flat and so ended thirteen straight months of decline. Two months does not make a market, but it is the clearest turn in the natural diamond price data since early 2025.
If you are shopping for a champagne diamond, the useful thing to know before reading any of it is which stones the index counts. It counts the diamond we compare yours against. It does not count yours.
What RAPI measures, in its own words
Rapaport prints the definition at the foot of every monthly release. The RAPI is "the average asking price of the 10% lowest-priced round diamonds in each of the top 25 quality categories (D-H, IF-VS2, GIA-graded, RapSpec-A3 and better) offered for sale on Rapaport Trade".
Four limits in that sentence decide how much of it applies here.
Color runs D to H. That is the colorless and near-colorless end of GIA's D-to-Z scale. The white-scale stones on this site start at K, three letters below H, and each carries a brown notation printed beside the letter — Faint Brown, Very Light Brown or Light Brown. The fancy-scale browns carry no letter at all, because they are graded on GIA's separate colored-diamond scale. Nothing inside RAPI's color window is a champagne diamond, and no part of the index is a proxy for one. What the notation itself means is set out in what "faint brown" on a GIA report means.
Clarity runs IF to VS2. SI and I grades are outside the index entirely, and a large share of the stones listed here sit in exactly those grades.
Shape is round only. Every other outline is outside it.
The prices are wholesale asking prices. They are offers made between trade members on Rapaport Trade, not retail tickets, and not records of completed sales. The retail listings this site indexes are asking prices too, which is worth holding onto: neither side of any comparison below is a sold price.
The August figures
| Size | July 2026 | August 2026 |
|---|---|---|
| 0.30 ct | +1.6% | +2% |
| 0.50 ct | +1.8% | +2.5% |
| 1 ct | flat | +0.5% |
| 3 ct | +0.2% | −0.4% |
The rebound is concentrated in the small end. Rapaport attributes the 0.30-to-0.69-carat gains to miners and manufacturers cutting production, and says 1-to-1.49-carat goods "stabilized amid inventory declines and reports of consumers cooling on lab-grown diamonds". The 3-carat index is the one that slipped.
One line in the August commentary is easy to misread: "Round diamonds performed better than fancies." In trade usage there, fancies means fancy shapes — pears, ovals, emeralds — not fancy-color grades. It is not a statement about brown or any other colored diamond, and RAPI tracks rounds only in any case.
Where it does touch a champagne diamond's price
Every card on this site shows a struck-through price: what a near-colorless diamond matched to that stone is listed at. The benchmark stone is G-to-H on the D-to-Z scale, matched to the champagne diamond on shape, on the same clarity grade, on cut quality, and on a carat weight inside a window that never crosses a trade price threshold; the figure taken is the lower quartile of those matched prices per carat. The method is on the prices page, and how our near-colorless price benchmark works explains what the resulting discount does and does not mean.
G and H sit inside RAPI's D-to-H window. So the index and our benchmark are describing overlapping material — the near-colorless side of the comparison — one at wholesale, one at retail. A sustained rise in near-colorless asking prices would, other things being equal, push the benchmark side of every card upward, and widen the gap shown against it. That is the honest description of the link, and it comes with two qualifications. Our benchmark matches each stone's own clarity, including the SI and I grades RAPI excludes, and it is drawn from live retail listings rather than a trade platform. And 0.5% in one month, on one side of a two-sided comparison, is a small number.
What this piece cannot tell you is whether our own discount has moved. The index here is rebuilt as a snapshot, and today's figures are today's; comparing them with a figure from a different build would compare two different populations of stones. Any claim about a trend in the champagne discount needs a matched series we do not publish.
What our index shows, 2026-09-09
2,733 unique verified natural brown diamonds, deduplicated by GIA report number, across 4,843 retailer listings at 9 retailers. Median live price $1,453, range $97 to $951,425. 2,431 stones are listed below their matched near-colorless benchmark, at a median discount of 47%. All asking prices, on one snapshot.
No index tracks the stones themselves
There is no published price index for brown-notation or fancy-brown diamonds. RAPI stops at H and at VS2; the general trade lists that quote per-carat prices are built around the same colorless-to-near-colorless material. A champagne buyer who wants a price signal has to take it from listings, and the strongest one available is not a market average at all.
Of the 2,733 stones here, 1,162 are listed by more than one retailer. Because stones are matched by GIA report number, those are the same physical diamond appearing at several stores at several asking prices, which is a difference you can act on immediately and without any view on where the market goes next. Why the same champagne diamond costs different amounts at different retailers covers how that gap arises and how to compare it.
What to take from it
If the small-round recovery holds, it is the part of the near-colorless market closest to the bulk of what is listed here: round is the largest shape pool on the index at 1,399 of the 2,733 stones, and much of it sits at and below one carat. A firmer white market makes the benchmark on those cards a higher number, not a lower one.
None of that argues for buying on a timetable. It argues for reading the two prices on a card as what they are — one live asking price set against another, in a month when the second kind has started to move. What the tint is worth per carat, band by band, is in the champagne diamond price guide.