Week 10, 2026

Median price per carat hit $1,136 this week, a seven-week low and down nearly 24% from the $1,493 recorded back in W04. That's not a blip. It's a sustained compression that's been running since early February, and it's now sitting 17% below the rolling average for this window. The broader median price fell to $1,119, also a record low for the period. More supply, softer prices. The direction is consistent.

Active inventory crossed 22.6 million stones, a record high across the seven weeks tracked and up more than 128% since W04. New listings came in at 1.87 million for the week, roughly half of last week's 3.47 million, so the flood has eased somewhat. But off-market activity ticked up 22% week on week to 338,873 stones. More listings disappearing, not fewer arriving. Combined inventory is still growing because the inflow, even at its reduced pace, comfortably outpaces the outflow.

Lab-grown share reached 61.2% of active inventory, another record for this window. The new listings breakdown tells most of the story: 1.39 million lab-grown stones listed versus 486,000 natural, a ratio of roughly 2.9 to one. Lab-grown median price dropped 16% week on week to $725.76, while natural held relatively firm at $1,350, up just over 1%. The curious number is lab-grown median price per carat, which rose 22.7% to $593.81. That's a composition effect worth watching: it suggests the new lab-grown listings skewed toward larger, better-spec stones rather than the budget-conscious volume that dominated recent weeks. Natural new listings, by contrast, dropped 59% from last week, likely reflecting the hangover after a heavy W09 restocking push by a handful of names that did most of the listing.

Cross-retailer overlap hit 45.7%, also a record for this window, up from 34.8% in W04. That means nearly half of all active stones appear across multiple retailers simultaneously, a pattern that typically compresses achievable margins and concentrates competition on price. The spread metric softened fractionally to 88.0% from 88.9% last week, still historically wide for this data set. Cushion cut was the standout shape mover, with median price jumping 21.7% to $1,350 on 95,891 new listings. Radiant added 6.1% to reach $1,049. Princess, trillion and the catch-all "other" category all fell hard, with princess down 22% to $740 and trillion off nearly 40% to $508. Round dominated volume at 41.1% of new listings, as it almost always does.

At the top end, a 5.08ct faint pink pear from GIA priced at $2.83 million held the most-expensive slot this week. A 36.21ct fancy cushion at $2.23 million and a 52.63ct fancy oval at $1.17 million round out the headline stones. Notably, two 10ct D VVS1 lab-grown stones, a radiant and an Asscher, each priced at $2.04 million, appeared in the top five by value. Lab-grown breaking into the seven-figure conversation is no longer unusual, but stones at that price point still attract attention.

With inventory at record levels and per-carat pricing at its lowest in seven weeks, the pressure on natural diamonds will come from how quickly that lab-grown overhang clears. If off-market rates accelerate from here, pricing may find a floor. If they don't, and new listings normalise around the 1.5 to 2 million weekly range, the compression probably has further to run. Cushion's sharp price move is worth revisiting next week: either it holds and signals genuine demand, or it reverts and confirms a composition quirk in this week's batch.

Lucy Market Index

Ten numbers I record every snapshot.

Versus Week 9, 2026

Biggest shape movers

Recent trends

How metrics are tracking across the recent window of snapshots.

How the Lucy Market Index has moved

By origin

Top shapes by new listings

Notable stones

Each stone links to its full Carat Hunter listing.