Natural Diamonds Fell 6.8% Last Week. Lab-Grown Did the Opposite.

Natural diamonds averaged a 6.8% weekly decline across more than 11 million listings. Lab-grown moved the other way, up 3.8%. That divergence doesn't happen every week, and understanding what's driving it matters before you spend anything.

The macro snapshot: naturals average $7,335 per listing, lab-grown $1,286. Over 30 days, both segments are actually down, naturals by 4.4% and lab-grown by 4.6%. So the week-on-week reversal in lab-grown isn't a confirmed trend change. But a 3.8% gain against a falling 30-day backdrop is worth tracking closely.

The shapes falling hardest

Large naturals took the biggest hits this week. Natural ovals in the 5 to 9.99 carat range dropped 63.66% on the week, continuing a 30-day decline of 46.89%. Natural marquise at 2.00 to 2.49 carats fell 54.21% this week and is down 51.23% over the past month. Natural radiant in the same weight range dropped 47.69%.

These three categories share a profile: heavier stones, J-K or H-I colour, included clarities, and price points that make them discretionary in the strongest sense. When buyers pull back, fancy shapes over 2 carats are always first to show it.

The 30-day data is the more honest signal. These aren't sudden corrections. They've been building for weeks, and this week accelerated the move. Anyone who held off buying a 2ct marquise or radiant over the past month effectively saved 40 to 50% without trying.

What's rising, and what to treat carefully

The strongest natural mover this week is natural rounds in the 0.20 to 0.29ct range, L-M colour, included clarity, up over 100% on the week. But 23 listings is not a market; it's a batch. One retailer repricing a parcel of small included rounds can move that bucket dramatically. Don't chase it.

More credible: natural rounds in D-E colour included clarities gained 61.66% this week and 51.26% over 30 days. Top colour paired with low clarity is an unusual combination, and the sustained 30-day trend suggests genuine repricing rather than noise. These are likely accent and melee stones where colour matters far more than clarity.

Lab-grown pears in the 1.00 to 1.24ct range gained 51.41% this week and 45.45% over 30 days. Pear continues to dominate fashion jewellery demand. Even included-clarity lab options in that weight range are finding buyers at rising prices. A 45% gain over 30 days is not noise.

Shape gaps and where the lab-grown argument is strongest

The price gap between natural and lab-grown isn't uniform. It varies meaningfully by shape, and those differences matter if you haven't locked in your shape preference yet.

Shape	Natural avg	Lab-grown avg	Lab discount
Marquise	$8,385	$1,147	86.3%
Cushion	$7,755	$1,140	85.3%
Pear	$8,894	$1,359	84.7%
Radiant	$7,352	$1,131	84.6%
Oval	$8,199	$1,582	80.7%
Round	$8,278	$1,988	76.0%
Princess	$5,122	$1,209	76.4%

Round and princess buyers get the smallest relative discount when choosing lab-grown over natural. Lab-grown rounds attract better cut quality and deeper demand, so retailers price them accordingly within the lab universe. A lab-grown round buyer is getting a 76% discount versus natural; a lab-grown marquise buyer is getting 86%. If you've committed to lab-grown but haven't committed to round, that gap has real dollar consequences at any price point.

Cross-retailer spreads are embarrassingly wide

Lab-grown rounds carry a 55.1% average cross-retailer spread this week. Natural rounds are at 54%. On a $2,000 lab-grown round, that's over $1,100 in potential overpayment depending on which retailer you approach first.

Shape	Origin	Avg retailer spread
Round	Lab-grown	55.1%
Round	Natural	54.0%
Pear	Lab-grown	44.4%
Oval	Natural	40.9%
Pear	Natural	35.8%
Marquise	Natural	29.4%

Natural marquise already fell sharply at the aggregate level this week, but that 29.4% retailer spread means some stores haven't passed those savings on yet. Comparing across retailers using the CaratHunter marquise search will quickly show whether the retailer in front of you is priced at the new market level or is still sitting on old inventory at old prices.

Lab-grown ovals have a 29.3% spread at an average price of $1,582. On a $1,500 lab oval, a 29% retailer premium is $435 you don't have to spend.

Three radiant H stones the market has mispriced

Our signals system flagged three natural radiant H colour stones at 1.50 carats this week, all priced 72 to 75% below the category median.

Specifically: $1,426, $1,485, and $1,605. The median for natural radiant H in that weight range sits at $3,875 per carat. These three are priced at $950 to $1,070 per carat.

H colour in a radiant cut is a comfortable choice for most buyers: visibly white face up in a yellow gold setting, warm enough to look luxurious, and well below the D to G colour premium. A 1.50ct natural radiant H at under $1,500 is not a normal market price. Current listings in this category are worth checking before they reprice.

There's also a natural round I colour at 2.01 carats for $3,191, flagged at 69% below the category median of $5,123 per carat. I colour in a white metal setting shows warmth, and that rules it out for some buyers. But for anyone who has already settled on I colour for the size it buys, this stone is priced well outside its peer group.

One more signal worth noting: a lab-grown fancy vivid blue marquise at 3.01ct, priced at $4,520, flagged at 31% below the category median. Fancy coloured lab-grown stones sit in their own market segment, and a 31% discount from median in a relatively stable category is a meaningful gap. Most of what our system flags at this severity in a week isn't coloured stones. This one is.

Supply is building in natural rounds

The natural round market absorbed 177 new listings in the 0.30 to 0.49ct range this week, with zero delistings. The 0.50 to 0.74ct range took 106 new listings. The 1.00 to 1.24ct bucket added 95. Even the 2.00 to 2.49ct range added 47, bringing that segment to 347 total listings.

Zero delistings across every weight bucket in the same week is the detail to focus on. Sellers are adding stock and not pulling anything. That combination builds inventory pressure that typically feeds through to softer pricing within a fortnight.

Lab-grown rounds in the same size range were static: no new listings, no delistings. A flat supply environment alongside rising prices is exactly the data you'd want to see if you're trying to confirm whether the lab-grown reversal this week has legs.

What I'm watching next week

The large natural oval decline is the one I keep returning to. A 63.66% weekly drop building on a 46.89% 30-day slide means this category is in genuine distress. At some point the pricing attracts buyers who see relative value, and when that happens the reversal can be fast. I want to see whether buying interest emerges at these new levels, or whether the category keeps falling.

Lab-grown pears are the other one. A 51% gain in a week is a fast move. If it holds or continues next week, the market is genuinely repricing this category after a long period of softness. If it gives back half the gain, it was a batch repricing by a handful of retailers that the broader market didn't follow.

Natural round supply is the sleeper story. A flood of new listings across every weight range, no delistings anywhere. If you're buying a natural round under one carat and you're not in a rush, watching for another week costs nothing and may save you a few hundred dollars.

The exceptional value signals in the radiant category are the most time-sensitive finding this week. Stones priced 72 to 75% below their category median get noticed and repriced. Usually within days.