The Diamond Price Index

Which way is the diamond market moving?

A daily, quality-banded price index for natural and lab-grown diamonds — not what any one diamond costs, but which way the market has moved. For what a specific diamond should cost, see Diamond Prices or The Diamond Brief.

As of September 6, 2026, The Diamond Price Index shows natural diamond prices down 3.5% and lab-grown diamond prices down 30.1%, for a 1.00ct round benchmark stone, since tracking began in March 2025.

Lab-grown prices have fallen roughly 8.6x faster than natural over the same period.

Historical Trend

Price Movement by Shape

Shown where 17 months of daily tracking clears our reliability checks: round, oval, princess and pear, both types. Cushion is withheld — its sample size is adequate, but it has an unexplained same-day swing we haven't yet traced to a cause, and we'd rather publish nothing than a number we can't stand behind. Marquise is withheld — too few listings on a typical day for a median to mean anything (same reason it's excluded from cross-shape pricing elsewhere on this site). 1Y where we have 12 months of history; full tracked period otherwise.

Methodology

Each figure above is the median asking price of a fixed benchmark stone — 1.00ct round, E–F color, VVS1–VVS2 clarity — sampled daily across our tracked live retail listings and indexed to 100 at the day we began tracking (March 2025). Days where fewer than 20 comparable stones are listed are omitted, not estimated: no number is published unless enough real listings exist to make a median meaningful.

What this index tracks today: our live listing feed is currently concentrated with a single major online retailer. We disclose this plainly rather than imply broader coverage than we have — the daily sample sizes shown next to each figure are the real, current count, so this is checkable, not asserted.

Natural and lab-grown are never blended into one figure — they are different, separately priced markets. Full methodology, including why we publish by quality band and the error that taught us to: Diamond Price Index Methodology →

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