Week 8, 2026

The number that stopped me this week was 6.23 million new listings hitting the market in a single seven-day window. That's an 185% jump on last week's already-elevated count, and it pushed active inventory to a record 17.9 million stones across the retailers I track. Total inventory value crossed $68 billion, up 67% week on week. Those are genuinely significant numbers. Not a seasonal blip, not a rounding quirk. A handful of names did most of the listing, with the top five retailers accounting for 57.6% of all new supply.

What makes the volume story interesting is what it did to the spread. The median price retailers charge for the same stone diverged to 85.7%, a record high over the window I can see. When supply floods in fast and unevenly, some retailers update their prices immediately and others lag, so spread widening of this magnitude is almost always a liquidity event rather than a genuine repricing. Buyers who take the time to compare the same certified stone across multiple listings are sitting on better arbitrage than at any point this year.

The per-carat price told a different story from the headline median. Median price per carat fell to $1,339.77, a record low for the window, down 10% from last week's $1,492.20. The overall median transaction price barely moved ($1,214 versus $1,201), which tells you the new supply skewed toward smaller stones: median active carat weight ticked down to 1.18ct. Natural diamonds came in at a median of $2,600 per carat, lab-grown at $667.44 per carat, a ratio of roughly 3.9 to one. Lab-grown's share of active inventory held almost perfectly flat at 59.0%, essentially unchanged from the prior week, so the volume surge wasn't disproportionately lab or natural. Both origins flooded in together.

Shape movements were split. Pear and emerald cut new listings both priced up notably, with pear median rising 14% to $1,341 and emerald up 13% to $1,275. Asscher went the other way hard, dropping 23% to $1,765, on the back of 130,000 new listings that appear to have repriced the category lower in a single week. Rounds dominated by volume as always, taking 37% of new listings at a median of $1,104, well below the market-wide figure, which reflects how much lab-grown supply anchors the round cut. Natural stone median price per listing jumped 18.5% to $1,849, though per-carat the move was modest (down 3.5%), so the size mix in incoming natural supply shifted toward larger stones.

Cross-retailer overlap rose to 43%, also a record for the window. More of the same certificates are appearing across more storefronts simultaneously. That's a compounding factor on top of the spread widening: not only are prices diverging on the same stones, but more stones are appearing in multiple places at once.

Going into week 9, the question is whether this supply wave normalises or continues to build. Off-market listings jumped threefold to roughly 400,000, which is elevated but nowhere near the 813,000 peak seen in week 6. If sell-through doesn't accelerate to absorb even a portion of 17.9 million active stones, expect the per-carat floor to test lower still. For buyers, this week's spread environment is about as favourable as it gets: search by certificate number, compare across the retailers I follow, and don't accept the first price you see.

Lucy Market Index

Ten numbers I record every snapshot.

Versus Week 7, 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.