Rapaport reported that diamond prices rose in September, with the strongest gains among smaller, higher-quality round stones. Its October 6 market report said the Rapaport Trade Diamond Index, or RAPI, increased 3.2 percent for 0.30-carat goods and 2.5 percent for 0.50-carat goods. The one-carat index rose 0.3 percent for a second consecutive month, while the three-carat index advanced 1.5 percent. The 0.30-carat index was up 15.1 percent year to date, and the 0.50-carat index was up 5.8 percent.
Those figures deserve attention, but they need context. RAPI tracks asking prices for a defined selection of round diamonds in specified quality ranges listed on Rapaport Trade. It is not a record of every diamond transaction, a retail price index, or a promise about the resale value of an individual stone. Rapaport attributed September’s gains to a combination of lower supply and rising demand. It also reported that small, lower-quality goods continued to face pressure from lab-grown competition.
The report offers a useful snapshot of a market that is moving unevenly. U.S. retailers were actively buying round diamonds, and Rapaport said demand for certain one- to two-carat goods continued to recover. The report also described solid demand for diamonds of two carats and above. At the same time, trading was seasonally quiet in several centers, Chinese attendance at the Hong Kong show was limited, and smaller lower-quality stones remained difficult to move.
For Martin Rapaport, the month’s price data sits within a longer public argument about how natural diamonds should be described and valued. Rapaport has spent decades advocating for the natural diamond trade and for clear separation between natural and laboratory-grown diamonds in commerce. In April 2026, the Rapaport Group formalized a Natural Diamond Policy stating that its trading platform, price list, and services would support natural diamonds and would not promote synthetic alternatives. That is the company’s stated commercial policy and position, not an independent finding that one category is superior for every buyer.
De Beers is pursuing its own response to the market downturn through consumer marketing and a renewed focus on natural diamond desirability. Its 2026 interim results said finished diamond jewelry sales were stable year over year, with natural diamond jewelry sales returning to growth among U.S. independent jewelers. The same report showed the scale of the continuing pressure: De Beers’ first-half revenue fell to $1.6 billion from $2.0 billion a year earlier, and its average realized price declined 32 percent to $105 per carat. De Beers attributed that price decline to product mix and a lower rough diamond price index. The company also said lower-value categories remain under pressure and that lab-grown retail prices continue to fall.
The September gains therefore mark a positive signal in selected natural diamond categories, not a blanket market recovery. Rapaport’s data, its natural-only policy, and De Beers’ marketing efforts show different parts of the industry’s response: tracking prices, making a clear trade position, and trying to strengthen consumer interest. For shoppers, the distinction is practical. Natural and laboratory-grown diamonds are both diamonds, but they have different origins, supply dynamics, pricing histories, and resale markets. The right choice depends on what the buyer values and what the seller can substantiate.
