Rapaport 2025 Diamond Price Statistics Annual Report Reveals Key Market Trends

Since 2005, a D, internally flawless diamond has performed very differently depending on how much it weighs. That single finding, drawn from Rapaport USA Inc.'s Diamond Price Statistics Annual Report released March 12, 2026, reframes how collectors and buyers should think about size as a value driver: 3-carat and 5-carat D-IF stones increased in value over that two-decade span, while their 1-carat counterparts declined.

The report, which Rapaport positions as its annual deep-dive into how various sizes, cuts, and clarities performed across 2025, also provides forecasts for 2026. It tracks performance using two distinct indices. The Rapaport Diamond Index, or RDI, measures the average Rapaport Price List price for D-H, IF-VS2, RapSpec A3+ diamonds. The RapNet Diamond Index, known as RAPI, takes a different approach: it captures the average asking price in hundreds of dollars per carat for the 10% lowest-priced round diamonds available on RapNet, restricted to GIA-graded stones in the D-H, IF-VS2 range meeting RapSpec A3 or better standards. The distinction matters because RDI reflects list pricing while RAPI reflects actual market asking behavior at the competitive lower end.

The shape story is equally pointed. Among pear-shaped diamonds, 1-carat goods sold at the most significant discounts to their round counterparts. Within that pear-shape category, however, quality proved protective: over the past five years, high-quality 1-carat pear shapes retained their value better than lower-quality stones of the same size. The report's chart data covers size categories from 0.50 carats through 1, 3, 5, and 10 carats, with clarity bands spanning D-IF, F-VVS2, H-VS2, and K-SI2, giving a granular picture of where value held and where it eroded.

The report's internal labeling reflects its dual identity: published in March 2026, it carries an internal header reading "Annual Report 2025," signaling that the data analyzed covers 2025 market performance rather than the current calendar year.

For anyone buying a diamond right now, the size-and-quality calculus the report lays out is practical rather than abstract. A 1-carat D-IF stone is not a safe store of value on the long-term data Rapaport has tracked; a 3- or 5-carat stone in the same quality tier tells a different story entirely. And within the pear-shape market, chasing lower prices by compromising on quality has, over five years, come at a measurable cost to value retention. The full report, including complete RDI and RAPI numeric series and the 2026 forecast analysis, is available through rapaport.com and rapnet.com.