Diamond Market, August 2026

The most striking thing about August is the split between scale and price. Total inventory value crossed $113 billion for the first time in the seven months I've been tracking it, a 15% jump from July's $98.3 billion. But the median price per carat fell to $937.50, its lowest point across that same window. More stones, more money in aggregate, cheaper per carat. That's the August story.

The price compression has been building quietly. Median price per carat has drifted down more than 21% since February, and the median listed price of $1,063.80 is also a seven-period low, down from $1,157 at the start of the year. None of this is panic, exactly. The decline has been gradual, and the market is still functioning normally by most measures. But buyers haven't had better entry points in recent memory, and the active inventory median of 1.22ct means there's no shortage of stones to choose from.

Lab-grown share stayed almost exactly where it was in July, at 63.6% of active inventory. The direction remains gently upward over the six-month window but August shows the pace has slowed to nearly nothing. The largest stone listed this month was a 77.78ct lab-grown cushion with IGI certification, priced at $115,298, which tells you something about how far lab-grown has pushed into territory that simply didn't exist commercially a few years ago. Natural stones still dominate the headline price records: the most expensive listing was a 50.5ct natural pear, D colour, VS1, certified by GIA, asking $4.84 million.

Shape movements were the most volatile part of the month. Asscher was the standout performer, with its median price rising 18.25% to $1,970 on 102,318 new listings. That's a meaningful move for a shape that typically plods along. Trillion had the worst month of any shape, falling 30.3% to a $701.52 median, though with only 2,513 new listings the sample is thin enough that single large lots can swing the number. Cushion was the more consequential story: down 25.5% to $1,333.50 on over 400,000 new listings. That's a real price shift at real volume. Round continued to dominate listings at 40.1% of new volume, with a $790 median that keeps it accessible relative to the fancy shapes.

The cross-retailer spread compressed again. At 81.9%, the median price gap between the cheapest and most expensive listing for the same stone is at its lowest point in seven months, down from 93.7% in March. More overlap between retailers, tighter pricing, less arbitrage on the table for buyers who shop around. The overlap rate itself, at 50.2%, is the highest it's been this year, which tends to accompany that spread compression: when more retailers carry the same inventory, prices converge.

With new listings still falling and prices at multi-period lows, the next few months will tell us whether the supply side is adjusting to softer demand or simply digesting a buildup. Cushion and marquise are worth watching closely. Both shapes had heavy new listing volume and significant price drops in August. If they don't recover in September, it may signal that buyers have quietly moved on.

Diamond Market Charts, August 2026 (August 2026)

The five charts below summarise what the diamond market did during August 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.

Versus July 2026

Biggest shape movers

Recent trends

How metrics are tracking across the recent window of snapshots.

How the Lucy Market Index has moved

Top shapes by new listings

Notable stones

Each stone links to its full Carat Hunter listing.