Diamond Market, Week 38, 2026

Week 38 brought 4.4 million new listings, the most I've recorded across six weeks of tracking, and the median price fell to $1,018.54, its lowest point in five periods. Those two facts belong together. When supply floods in at this rate and barely anything exits the market (just 34,715 off-market listings, also a six-period low), prices don't hold. A handful of names did the bulk of the listing: the top five retailers accounted for just under half of all new volume this week. Total active inventory now sits at 40.4 million stones, another record, and the combined value across the retailers I track has climbed to $128.8 billion. It's a big market getting bigger, but the buyer at the mid-range is paying less per stone than at any point in recent weeks.

The spread story is genuinely significant this week. Cross-retailer overlap has fallen to a six-period low of 43.8%, meaning more retailers are carrying stones that nobody else has on offer. At the same time, the median multi-retailer spread has climbed to a record 84.9%. That's the gap between what you'd pay for the same stone at the most expensive retailer versus the cheapest, and it reinforces the overlap story: when inventory is more fragmented, pricing discipline loosens. For a buyer willing to shop around, it's real money. On a $1,500 stone, a spread of that size could mean the difference between paying $1,000 and $1,850 at different retailers.

Lab-grown share edged down to 61.7% of active inventory, its lowest reading over six weeks and a few points below the 64.7% peak recorded in early August. The shift is gradual, not dramatic. Lab-grown still accounted for the majority of new listings this week: 2.7 million versus 1.7 million for natural, so the mix is moving slowly. The pricing gap between the two origins remains wide. Lab-grown median landed at $618 this week, natural at $1,590. Per carat, the story is starker: lab-grown runs at $275.70, natural at $2,646. That's not a niche price difference. It's a structural one.

Shape volumes were dominated by round, as they almost always are: 2.2 million new listings at a median of $680. Oval came second with 654,000 listings and an $858 median, with pear, emerald, cushion, and heart all clustering between $1,075 and $1,128. Radiant stands apart at a $1,298 median, the highest of the major shapes this week. At the top end, the most expensive stone I saw listed was a 38.62ct natural H IF round, GIA-certified, at just under $3 million. On the lab-grown side, a pair of 55.33ct J VS1 radiant stones are sitting on the market at prices ranging from $54,000 to $140,000 at different retailers, a gap that tells you a lot about how loosely priced large lab-grown stones remain.

With off-market activity at a six-period floor and new listings at a six-period ceiling, the inventory surplus will keep building unless demand picks up. Price per carat has held remarkably steady despite the volume surge, sitting at $932.39 versus $930.58 six weeks ago. That stability is worth watching. If it cracks as inventory continues to rise, the median price has further to fall. If it holds, it suggests the new supply is being absorbed somewhere below the surface of the aggregate data.

Diamond Market Charts, Week 38, 2026 (14 to 21 September 2026)

The five charts below summarise what the diamond market did during 14 to 21 September 2026. Each is a static image you can save or share. Together they cover where prices sit today, how inventory is moving, the lab-grown versus natural mix, where retailers raised or cut prices, and how much the same stone can vary across competing sellers.

Lucy Market Index

Ten numbers I record every snapshot.

Counted listing rows; from October 12, 2026 we count new stones.

Versus Week 37, 2026

Recent trends

How metrics are tracking across the recent window of snapshots.

How the Lucy Market Index has moved

By origin

Counted listing rows; from October 12, 2026 we count new stones.

Top shapes by new listings

Notable stones

Each stone links to its full Carat Hunter listing.