Natural Diamonds Dropped 6.4% This Week. Lab-Grown Rose.

The week in two numbers

Natural diamonds dropped 6.4% across 6,044 tracked categories this week. Lab-grown diamonds climbed 5.6% across 4,799 categories. That's a meaningful divergence. For most of 2026, these two markets have moved in loosely similar directions on a monthly basis (both still sit down around 5.3% to 5.4% over the past 30 days). But this week they split, and the gap tells you something about where demand is actually landing.

The average natural diamond in our dataset sits at $7,261. The average lab-grown stone: $1,339. That's an 81.6% gap on average, though it varies wildly by shape. Marquise cuts show the widest spread at 86.2%, meaning a lab-grown marquise costs roughly one seventh of its natural equivalent. Rounds and princess cuts sit at the narrow end, around 72.4% and 72.6%, which still means you're paying three to four times more for natural in those shapes.

What moved (and what cratered)

The biggest mover this week was lab-grown ovals in the 1.00 to 1.24ct range, J to K colour, I clarity. They jumped 84.5% in seven days, after already climbing 197% over the past month. Before you get too excited: these are lower colour, lower clarity stones, and 140 listings means the category isn't enormous. But the trajectory is steep. Demand for affordable lab-grown ovals in that "just over a carat" sweet spot is clearly strong, and supply hasn't caught up.

On the natural side, small rounds (0.30 to 0.49ct) in N+ colour and I clarity absolutely collapsed. Down 82.6% in a single week. That's not a gentle correction. With 139 listings, there's enough volume to take seriously. Large natural pears (5.00 to 9.99ct, J to K, I clarity) also fell hard, losing 48.4%. And natural cushions in the 0.30 to 0.49ct range, F to G colour, I clarity, dropped 46.0%. The 30 day numbers confirm these aren't blips: the pear and cushion categories are both down 47% plus over the month.

One natural category did rise. Radiants in the 0.30 to 0.49ct range, N+ colour, I clarity jumped 41.0% this week, though on a 30 day view they're only up 9.6%. Small sample (45 listings), but it's a reminder that not every natural category is sliding.

Category	Origin	7 Day Move	30 Day Move	Listings
Round 0.30 to 0.49ct, N+, I	Natural	Down 82.6%	Down 30.9%	139
Pear 5.00 to 9.99ct, J to K, I	Natural	Down 48.4%	Down 47.7%	20
Cushion 0.30 to 0.49ct, F to G, I	Natural	Down 46.0%	Down 47.2%	29
Oval 1.00 to 1.24ct, J to K, I	Lab-grown	Up 84.5%	Up 197.2%	140
Round 0.20 to 0.29ct, D to E, I	Lab-grown	Up 53.8%	Up 63.1%	152

Natural diamonds are taking the biggest hits in lower colour and clarity grades. Buyers aren't willing to pay natural premiums for stones that don't look premium. If the colour and clarity won't impress, lab-grown wins on price by such a margin that the lower quality naturals simply can't compete.

The supply flood

Supply numbers this week are dramatic. Lab-grown rounds in the 0.30 to 0.49ct range saw supply jump 511%. Natural rounds in the 1.00 to 1.24ct range climbed 418%. Natural 1.50 to 1.99ct rounds went up 225%.

Some context on the lab-grown number. The actual listing activity (2 new, 15 delisted) suggests this is inventory reshuffling rather than a genuine production surge. The natural 1.00 to 1.24ct round figure is more telling. With 73 new listings against 49 delistings in a single week, that's real new supply entering the market. And with natural prices already sliding 6.4% on average, more supply is the last thing sellers want to see.

For buyers, more supply means more competition between retailers, and more competition means better prices. If you're shopping for a 1ct to 1.24ct natural round, the next few weeks could bring solid deals as retailers work to move freshly listed inventory.

Lab-grown ovals in the 1.00 to 1.24ct range also saw supply surge 128%, with only 2 new listings and 12 delisted. Despite that supply increase, prices in the lower colour grades still jumped. Demand is outrunning inventory in that category, which is unusual. Most of the time, supply increases pull prices down. When they don't, you know the buying pressure is real.

Where retailers are overcharging (and where they're not)

This is the part I care about most. Cross-retailer pricing data shows genuinely massive spreads this week, particularly on rounds in the 0.46ct to 0.50ct range.

We flagged five high severity arbitrage signals, all on rounds. The worst: a 0.46ct round listed across 9 retailers, with the cheapest at $367 and the most expensive at $1,001. That's a $634 spread. A 173% markup from bottom to top. Another 0.50ct round showed a $546 spread across 7 retailers, ranging from $398 to $944. These aren't obscure stones. Half carat rounds are one of the most popular engagement ring categories.

Stone	Cheapest	Most Expensive	Spread	Retailers
Round 0.46ct	$367	$1,001	$634 (173%)	9
Round 0.50ct	$398	$944	$546 (137%)	7
Round 0.46ct	$384	$1,001	$617 (161%)	7
Round 0.48ct	$400	$871	$471 (118%)	6
Round 0.46ct	$381	$831	$450 (118%)	7

You could pay $1,001 for a stone available for $367 elsewhere. Same carat weight, same characteristics, listed by retailers you've heard of. The difference is pure markup.

On the retailer side, The lowest-priced retailer in our index continues to lead on cohort price, averaging about 10.5% below the cross-retailer median across ~1,400 active listings. The largest retailer in our index (around 126,000 active listings) sits roughly 3.7% above the median , reasonable given its scale. At the other end, one small-inventory retailer averages about 115.7% above the cohort median across ~700 active listings, which means equivalent stones cost more than double the market rate on average. They may deliver something in service or presentation that justifies a premium, but the stone pricing alone is tough to justify when you can compare identical specifications across dozens of retailers.

Lab-grown by shape: where the real value sits

Not all lab-grown discounts are created equal. The gap between natural and lab-grown varies by more than 13 percentage points depending on which shape you pick.

Shape	Natural Avg	Lab-grown Avg	Discount
Marquise	$7,631	$1,053	86.2%
Cushion	$7,578	$1,137	85.0%
Radiant	$7,472	$1,144	84.7%
Pear	$8,465	$1,366	83.9%
Round	$8,358	$2,306	72.4%
Princess	$4,472	$1,226	72.6%

Marquise buyers get the biggest bang from going lab-grown, saving 86 cents on every dollar compared to natural. Cushion and radiant follow close behind at 85.0% and 84.7%. Rounds and princess cuts offer the "smallest" discount, though calling 72% small feels absurd.

Rounds hold a narrower gap because lab-grown round production is mature, demand is highest, and pricing has already compressed over years of market development. Fancy shapes like marquise and cushion still carry less lab-grown supply relative to demand, so the natural comparison looks more extreme.

If you're considering a marquise or cushion and you're open to lab-grown, the maths is hard to argue with. A natural cushion averaging $7,578 versus a lab-grown cushion at $1,137 is a $6,441 difference. That's a honeymoon, or most of a setting upgrade, or simply money you keep.

Cross-retailer savings you should be chasing

Beyond individual arbitrage signals, the broader cross-retailer data tells a consistent story. Lab-grown rounds average a 65.6% cross-retailer savings percentage, meaning the spread between the cheapest and most expensive retailer for comparable stones is enormous. Lab-grown ovals sit at 46.2%, and natural rounds at 45.0%.

Even lab-grown marquise, where the absolute dollar spread averages $317, shows a 16.7% saving. On a $1,900 stone, that's $317 you don't need to spend. And for lab-grown emerald cuts, the average spread hits $303 at 18.8%.

Every shape, every origin, every price point: comparing across retailers saves money. Not sometimes. Every time. The only variable is how much.

What I'm watching next week

Three things on my radar.

The natural diamond slide. A 6.4% weekly drop is notable. Another week like this and we're looking at a trend, not a wobble. The 30 day average is already down 5.4%, so the trajectory is steepening. I'll be watching whether natural round prices stabilise or keep falling, especially with 73 new 1ct to 1.24ct listings hitting the market this week alone.

Lab-grown oval supply. The 1.00 to 1.24ct category spiked 128% in supply, and prices in the lower colour grades still jumped 84.5%. Normally those two forces cancel each other out. If supply catches up to demand, the price gains won't hold. But if demand keeps outpacing new inventory through May, lab-grown ovals in that carat range could have further to run.

That small-inventory retailer's cohort spread. At about 115.7% above median, it's one of the widest average premiums we've measured in the dataset. Whether their pricing adjusts as competition intensifies or stays put because they're serving a segment that doesn't compare, it's a number worth keeping an eye on.

The natural market feels wobbly right now. Lab-grown feels like it's found a short term floor and is bouncing off it. If you're buying natural, be patient and compare aggressively across retailers. If you're buying lab-grown, the deals are already good, but fancy shapes (marquise, cushion, radiant) offer the most dramatic savings versus natural equivalents. And whatever you're buying, check at least three retailers before you commit. The data says you'll thank yourself.