Diamonds may not be forever, at least in value (opens the source in a new tab)
- A standard one-carat natural diamond averaged about $3,898 in September 2026, down 51% from $8,007 in September 2021, according to Rapaport data.
- Lab-grown stones, chemically identical, were in 61% of engagement rings sold in 2025, The Knot’s study finds; a comparable lab stone costs about $450, against $2,800 to $3,200 for a natural one.
- The market is splitting: mid-range natural stones are most exposed, larger and rarer gems are holding up, and De Beers is halting its Venetia mine for more than two years to curb supply.
- −51%
- one-carat price since 2021
- 61%
- engagement rings with lab stones
Why it matters For anyone holding jewellery as savings, ordinary diamonds now behave like consumer goods; only rare, large stones still act like assets.
Watch next Rapaport’s one-carat index was flat in August after 13 months of falls, and De Beers’ supply cut could put a floor under prices.