Small rounds surged 60% while big cushions quietly collapsed

Natural diamonds slipped 0.88% this week on average while lab-grown went the other direction, gaining 2.72%. Looking at the past 30 days, the picture flips entirely: naturals are up 5.70% while lab-grown has fallen 5.96%. Two markets, genuinely divergent trajectories, and neither one telling a tidy story.

The averages set the stage but don't carry the plot. Natural rounds average $8,561 across more than 10 million listings. Lab-grown rounds average $2,036. A 76% price gap for the most-traded shape in the market. And yet the weekly signal coming out of both categories is choppier than that headline spread suggests.

Where small naturals caught fire

The biggest mover this week was a category most buyers never consider: natural round stones in the 0.20 to 0.29ct range, J-K colour, included clarity. Median prices jumped 62.68% in seven days. These are accent and cluster stones sitting at an $806 median, not centrepieces anyone shops for deliberately. But a 62% move in a week across 60 listings is a signal something is happening in this corner of the market, even if the dollar amounts are small.

Natural rounds in D-E colour with included clarity jumped 61.66% over seven days, to a $1,221 median. D-E colour in a round brilliant is top tier territory regardless of clarity. Buyers trading down on clarity to access premium colour are paying more for that trade-off than they were a week ago. Whether this is a genuine demand shift or thin-market noise is something worth tracking.

Lab-grown pear shapes in the 1.00 to 1.24ct range, H-I colour, included clarity, rose 51.41% over seven days and are up 45.45% over the past month. At a $1,994 median, this category has repriced significantly. A month of sustained gains in lab-grown fancy shapes is not common. Worth watching to see if demand or supply dynamics are shifting for this cut.

Natural radiant cuts in the 0.30 to 0.49ct range, N+ colour, included clarity, are also up 40.97% in seven days. At a $3,855 median on 189 listings, this is a larger sample than most of the other movers this week, which makes the move more notable. Low-colour fancy shapes in smaller sizes don't usually make the top of the movers list.

Where big naturals fell hard

The declines on the other side of the ledger are genuinely significant. Natural oval stones in the 5.00 to 9.99ct range, F-G colour, included clarity, fell 47.65% in a week. That's 20 listings with a $25,891 median. Thin markets move fast when a couple of sellers reprice, and this category is thin. But a 47% drop, even in a 20-stone market, is not a number to ignore.

Natural cushion cuts in the 3.00 to 3.99ct range, F-G colour, included clarity, fell 39.58% in a week and are down 34.91% over 30 days. Twenty-three listings at an $8,586 median. The 30-day trend confirms this is sustained, not a blip. If you're currently trying to sell a large natural cushion, the market has moved against you, and it's been moving for a month.

Lab-grown rounds in the 1.00 to 1.24ct range, N+ colour, included clarity, dropped 49.39% in a week and are down 50.42% over the past month. These sit at a $452 median after the fall. A 50% drop over a month in the most-traded shape in the lab-grown market tells you something meaningful about where demand for low-colour lab-grown product currently sits.

Category	Median Price	Change (7 days)	Change (30 days)
Natural round 0.20 to 0.29ct, J-K, Included	$806	+62.68%	+29.66%
Natural round D-E, Included	$1,221	+61.66%	+51.26%
Lab pear 1.00 to 1.24ct, H-I, Included	$1,994	+51.41%	+45.45%
Natural oval 5.00 to 9.99ct, F-G, Included	$25,891	-47.65%	-48.93%
Natural cushion 3.00 to 3.99ct, F-G, Included	$8,586	-39.58%	-34.91%
Lab round 1.00 to 1.24ct, N+, Included	$452	-49.39%	-50.42%

Lab versus natural prices, by shape

The gap between lab-grown and natural prices varies more by shape than most buyers realise, and some of those gaps are more rational than others.

Rounds sit at 76.2%, princess at 76.1%. These are the tightest gaps in the market and also the most-traded shapes. Competition keeps them closer. Marquise sits at 87.5% and baguette at 87.2%. An average natural marquise at $9,021 versus $1,130 for a lab-grown marquise is the sort of comparison that makes buyers pause.

Shape	Natural Avg	Lab Avg	Gap
Marquise	$9,021	$1,130	87.5%
Baguette	$4,025	$516	87.2%
Cushion	$7,871	$1,186	84.9%
Pear	$9,111	$1,431	84.3%
Heart	$7,409	$1,268	82.9%
Emerald	$7,529	$1,318	82.5%
Round	$8,561	$2,036	76.2%
Princess	$5,248	$1,255	76.1%

The baguette gap at 87.2% is worth noting for anyone considering an east-west or accent stone setting. A lab-grown baguette at $516 average versus a natural at $4,025 is a significant decision point, particularly in settings where the baguette is a side stone rather than the centrepiece.

The cushion gap sits at 84.9% and the pear gap at 84.3%. Both are shapes with strong demand on the natural side but aggressive lab-grown supply. When those large natural cushion prices are also falling 35% over 30 days while lab-grown cushion prices stay relatively stable, the lab-grown option starts looking less like a compromise and more like the logical choice for buyers who care about price-to-quality.

Where retailers diverge the most

Cross-retailer spreads this week are significant enough to mention explicitly. Natural emerald cuts carry a 63.7% average saving versus the priciest retailer, with a 72% average price spread across the market. Natural rounds carry a 56.6% average saving, and lab-grown rounds a 59.9% average saving.

Natural marquise cuts are worth singling out separately. They carry the widest lab-natural price gap at 87.5% and a 42.7% average cross-retailer saving. A buyer shopping a natural marquise without comparing retailers is likely paying 42% more than they need to for the same category of stone.

Buyers who compare natural emerald cut prices across retailers are finding savings that, on a 1.5 carat stone, can exceed $4,000. For lab-grown rounds, cross-retailer comparison produces average savings of nearly 60%.

Category	Avg Price Spread	Avg Saving vs Priciest Option
Lab round	75.5%	59.9%
Natural emerald	72.1%	63.7%
Natural pear	71.5%	48.0%
Natural oval	69.0%	50.2%
Natural round	78.5%	56.6%
Lab pear	107.0%	44.8%

The natural oval and pear spreads at 50% and 48% average savings point to a market where retailers have not converged on consistent pricing. Some part of that spread reflects genuine quality differences between stones. But cross-retailer comparison on oval diamonds consistently reveals that a meaningful portion of the spread is pure markup, not quality.

Supply flooding into small natural rounds

The supply data this week deserves attention. Natural round cuts in the 0.30 to 0.49ct range saw supply jump 1,320% in seven days, landing at 1,165 listings after two new stones entered from a very low starting base. The 0.50 to 0.74ct range is up 511.88%, the 1.00 to 1.24ct range up 401.12%.

These are percentage changes off a small base, not an absolute flood. But the direction is consistent across three adjacent carat buckets in the same shape. Natural round supply at the sub-1.25ct range expanded significantly this week, and with average natural prices down 0.88% simultaneously, there is downward pressure building.

For buyers currently shopping natural rounds in these size ranges, the short-term supply picture suggests prices are more likely to soften than spike. That's not a reason to wait indefinitely, but it's a reason not to panic-buy at the first well-priced stone you find.

The fancy colour exception

Market signals this week flagged five natural round stones in the 1.00 to 1.24ct range priced between $141 and $146. The median per carat for that category is $1,561. These stones sit at $113 to $129 per carat, described as yellow, brown, grey-green, and yellow-grey fancy coloured rounds.

The 92 to 93% discount versus the category median is technically accurate but needs context. Fancy coloured rounds with secondary or muted colour modifiers trade at steep discounts to white diamonds of the same weight. These aren't "cheap" D-E rounds. They're fancy coloured stones with earthy or off-tonal hues that sit in a different market entirely.

If you're open to a fancy coloured natural diamond as an accent piece or something unconventional, this end of the market has product at prices most buyers don't expect to find in the one carat and above natural range. Just go in knowing what you're buying.

What I'm watching next week

The large natural cushion decline is the signal I'm most focused on. A sustained 30-day drop of nearly 35% in a specific size and colour range is starting to look structural rather than corrective. If the 3 to 4 carat natural cushion category shows continued decline next week, it may spill into adjacent fancy shapes at similar weights.

The lab-grown pear surge, 51% in a week on 29 listings, is the other signal worth verifying. One more week of gains would suggest genuine demand momentum in lab-grown fancy shapes. A reversal would confirm it was thin-market noise.

And the cross-retailer spreads on natural rounds aren't narrowing. Buyers comparing retailers on natural rounds are consistently finding 50 to 60% price differences for comparable stones. Until the expensive retailers start adjusting, that opportunity stays open.