Natural diamonds fell 4% this week. Large ovals took most of the damage.

Natural diamonds averaged down 4.1% over the past seven days. That's a real number, not noise, and it demands an explanation. Lab-grown moved a quieter 0.57% lower on the week but has shed 5.9% over thirty days. Two markets, two different problems.

Two markets, two different problems

The seven day fall in natural doesn't mean the market is collapsing. The thirty day number is actually up 2.7%, which means something specific happened this week rather than a structural unravelling. My read is that the damage is concentrated in the larger fancy shapes, which fell sharply after what looked like an extended run. More on that below.

Lab-grown is a slower moving story. The weekly dip is almost nothing. But 5.9% off over thirty days is consistent pressure, not a correction. With 18.4 million lab-grown listings across 5,276 categories compared to 9.9 million natural listings across 6,521 categories, supply in lab-grown is vast and keeps growing. That supply doesn't disappear; it just gradually erodes price floors.

What moved up, and why

The biggest single weekly mover in natural diamonds is an unlikely one. Natural round brilliants in the 0.20 to 0.29 carat range, J-K colour, included clarity, jumped 87.8% in seven days. 57 listings all moved together. That's not one outlier inflating the median; that's a coordinated shift in a small category, probably driven by restocking activity from jewellery manufacturers sourcing side stones. If you need accent rounds in J-K at this size, this week was the wrong time to shop.

Natural rounds in D-E colour, included clarity, rose 61.7% on the week and 51.3% over thirty days. Buyers chasing that colourless look without caring about inclusions have been active in this corner, and sellers have responded. The included clarity tradeoff makes sense when you're going for colour above all else.

The move that caught my attention is in lab-grown. Pear-shaped lab-grown stones, 1.00 to 1.24 carats, H-I colour, included clarity, rose 51.4% on the week and 45.5% over thirty days. 31 listings, consistent direction. Pear shapes have been getting significant style attention lately, and this looks like demand catching up to what was an underpriced category. Whether the move holds is worth watching.

Lab-grown rounds at 0.30 to 0.49 carats, L-M colour, included clarity, also rose 51.2% on the week, and this category is up 78.8% over thirty days. That sustained thirty day move is the strongest in the data. L-M colour is warmer than most buyers prefer, but at small sizes and low price points, value focused buyers are clearly not bothered.

The falls, which are the real story

Natural large ovals, specifically 5.00 to 9.99 carats, H-I colour, included clarity, dropped 54.4% in seven days and 46.9% over thirty days. 28 listings. That's a sustained, significant correction in a category that was running well above where fundamental value would put it. Large fancy shapes at the premium end have been overvalued relative to equivalent rounds for a while. This looks like the adjustment.

Natural radiants at 2.00 to 2.49 carats, J-K colour, included clarity, fell 45.6% on the week. Radiant cuts at two carats in J-K are a genuinely awkward specification because the warmth of J-K colour becomes more visible at that size. These stones are caught between buyers who want colour and buyers who want size, and neither group is biting.

Lab-grown rounds at 1.00 to 1.24 carats, N+ colour, included clarity, dropped 49.4% on the week and 50.4% over thirty days. Freefall is the accurate word. N+ colour at the one carat mark in lab-grown has no natural constituency of buyers. These stones compete on price alone, and even on price they're losing.

Category	Week change	Month change	Median price per carat
Natural oval 5.00 to 9.99ct H-I I	-54.4%	-46.9%	$4,919
Lab round 1.00 to 1.24ct N+ I	-49.4%	-50.4%	$580
Natural radiant 2.00 to 2.49ct J-K I	-45.6%	-32.0%	$3,901
Natural round 0.20 to 0.29ct J-K I	+87.8%	n/a	$890
Lab pear 1.00 to 1.24ct H-I I	+51.4%	+45.5%	$1,993

The natural pear at 0.30 to 0.49 carats, N+ colour, included clarity, fell 40.5% on the week but is up 6.2% over thirty days. 479 listings. That's a large pool bouncing around, not trending in one direction, and week on week volatility at that sample size usually reflects mix shift rather than a genuine price move.

The lab-grown discount by shape

The gap between natural and lab-grown prices is not uniform across shapes, and knowing where the gap is widest matters for buyers deciding which side of that divide they're on.

Shape	Natural avg	Lab-grown avg	Gap
Round	$8,534	$2,111	75.3%
Oval	$8,336	$1,621	80.6%
Emerald	$7,434	$1,314	82.3%
Cushion	$7,850	$1,228	84.4%
Marquise	$9,078	$1,148	87.4%
Baguette	$3,958	$515	87.0%

Rounds have the narrowest gap at 75.3%. Lab-grown rounds are the most commoditised category in the market, and demand there is strongest, so prices have held up relatively well. Still, $8,534 versus $2,111 is a substantial difference however you want to frame it.

Marquise at 87.4% and baguette at 87.0% are the widest gaps. A natural marquise averages $9,078; a lab-grown marquise averages $1,148. For a buyer who simply wants the visual drama of a marquise without caring about provenance, lab-grown is the obvious answer. For buyers who care about long term value retention, the maths are less simple.

The emerald cut gap at 82.3% stands out because natural emerald cuts are also the shape with the single largest cross-retailer pricing spread this week. Buyers facing an 82% gap between natural and lab-grown, and a 63% spread between retailers within natural, have a lot of decisions to make. Most are making them without the data.

Where retailers are miles apart

Natural emerald cuts show a 63.2% average spread between the cheapest and most expensive retailers for the same specification. That means the gap between the right and wrong retailer for a natural emerald cut could be tens of thousands of dollars depending on the stone size. Same certificate grade, same shape, completely different price.

Natural rounds come in at a 56.7% average spread. Lab-grown rounds at 60.2%. The lab-grown round market is enormous and liquid, so you'd expect prices to have converged by now. They haven't. Comparing lab-grown rounds across retailers remains one of the most reliable ways to find a real saving.

Shape	Origin	Avg cross-retailer gap
Emerald	Natural	63.2%
Round	Lab-grown	60.2%
Round	Natural	56.7%
Oval	Natural	49.5%
Pear	Natural	48.7%
Pear	Lab-grown	45.7%

Lab-grown pear shapes at 45.7% are interesting in light of this week's 51% price surge in that category. When prices are rising quickly but retailer spreads remain wide, the market hasn't settled on a consensus price yet. Some retailers are pricing in the new reality; others haven't caught up. That gap won't last, and buyers who move quickly can take advantage of it. Searching for lab-grown pear shapes right now surfaces the full range.

Two stones worth looking at now

The market signals flagged two specific opportunities this week that are worth naming directly.

A natural princess cut, G colour, 1.45 carats, is listed at $2,436. The median price per carat for that specification is $2,999. That puts this stone 44% below median, which is in genuinely exceptional value territory. A well-cut G princess at 1.45 carats is a good stone. Not a compromise. At $2,436, it deserves a close look from anyone shopping natural princess cuts in that size range.

The other opportunity is in large natural ovals. J colour stones at 5.02 carats are listed between $41,620 and $48,926 against a median of $78,200 for that specification (based on a $15,567 median per carat). That puts these at $8,291 to $9,746 per carat, a discount of 37% to 47% against median. These appeared in the same week that large natural ovals fell 54% overall, so some of the median comparison reflects last week's higher prices. Even adjusting for the correction, these are priced well below where this specification has historically traded.

J colour at five carats is visible. It's not for everyone. But in a halo setting, or mounted in yellow gold where the warmth reads as a feature rather than a flaw, J at the five carat mark can be beautiful. At $41,620 for 5.02 carats, buyers who know large ovals are operating in a very different market than they were two weeks ago. Worth knowing.

What I'm watching next week

The natural oval situation is unresolved. A 54% weekly fall after a 47% thirty day decline is a lot of correction in a short time. Either the market has found its floor, in which case buyers who moved this week will look prescient, or there's more to come. I'll be watching for new listings in the 5ct+ natural oval bucket and whether median prices stabilise.

Lab-grown pears bear watching for different reasons. 51% in a week on 31 listings is meaningful but not definitive. Continuation next week would suggest the start of a genuine rerating for that shape. A reversal would confirm noise.

The natural round supply story is the one with the most patience required. Listings in the 0.30 to 0.49ct bucket grew by more than 1,300% this week (from a low base), with meaningful additions across the 0.50 to 0.74ct, 1.00 to 1.24ct and 2.00 to 2.49ct buckets too. Rapid supply expansion usually precedes price softening. If you're buying natural rounds under one carat and you're not in a hurry, waiting a few weeks may get you a better number.