Natural Diamonds Slid Another 6% This Week While Lab Grown Quietly Rallied

Natural diamond prices fell 6.4% across nearly 7.7 million listings this week, pushing the rolling monthly decline to 9.5%. At the same time, lab-grown diamonds climbed 5.6% across almost 15 million listings, their strongest weekly performance in recent memory. Two markets, moving in opposite directions, with the gap between them widening further. If you're buying a diamond right now, the timing of your purchase and the market you're buying in both matter more than usual.

Natural diamonds can't catch a break

The average natural diamond in our database now sits at $6,888, down from roughly $7,600 just a month ago. But the headline average masks some truly dramatic moves in individual categories.

Natural round brilliants in the 0.30 to 0.49ct range with N+ colour and I clarity collapsed 82.6% in a single week. That's not a typo. With 261 active listings, this category saw its median price crater, likely driven by a wave of lower grade inventory flooding the market at aggressive prices. It's the kind of move that usually corrects partially the following week, but it signals genuine oversupply in the lower tiers.

Large natural stones took serious hits as well. Pear shapes in the 5.00 to 9.99ct range (J to K colour, I clarity) dropped 48.4% this week, compounding a monthly decline of 47.7%. At a median of $7,736 per carat, these stones are still expensive by any standard, but they're repricing fast. Natural ovals from 4.00 to 4.99ct in the same colour and clarity tier fell 40.3%, now down 42.1% over the past month, sitting at $6,946 per carat. Cushions from 3.00 to 3.99ct in F to G colour dropped 39.6% for the week and 34.9% for the month.

Larger natural stones in the mid to lower colour and clarity tiers are consistently under the most pressure. For buyers, that translates to real leverage. If you've been quoted a price on a 3+ carat natural cushion or pear in the J to K colour range, it's worth getting a fresh quote or comparing against current market data, because the stone you're looking at may be worth considerably less than it was four weeks ago.

Not everything dropped. Natural rounds with D to E colour and I clarity saw a 61.7% spike, though that category had only 40 listings and should be read cautiously. Small sample, big swing. Natural radiants in the 0.30 to 0.49ct range with N+ colour jumped 41%, another thin category where a handful of new listings can move the median significantly.

Lab-grown bounced, but don't call it a trend

Lab-grown diamonds averaged a 5.6% weekly gain, though the monthly picture is essentially flat at +0.1%. This looks like a sharp weekly bounce rather than a sustained reversal. The average lab-grown diamond in our database is priced at $1,274, roughly a fifth of the natural average.

The standout mover was lab-grown ovals in the 1.00 to 1.24ct range with J to K colour and I clarity, up a startling 84.5% on 112 listings. That's a category that was likely underpriced and corrected quickly once inventory thinned. Lab-grown rounds in the 0.20 to 0.29ct range with D to E colour and I clarity rose 53.8% across 182 listings, another correction in a segment where prices had dipped below sustainable levels.

Lab-grown prices remain dramatically below natural across every shape. The gap ranges from 72.3% on princess cuts all the way up to 85.8% on marquise.

Shape	Natural Avg	Lab-grown Avg	Gap
Marquise	$7,465	$1,061	85.8%
Radiant	$7,312	$1,119	84.7%
Cushion	$7,159	$1,165	83.7%
Pear	$8,097	$1,335	83.5%
Round	$8,152	$1,993	75.6%
Princess	$4,295	$1,191	72.3%

For a natural marquise averaging $7,465, the lab-grown equivalent averages $1,061. That's not a discount. That's a structurally different market.

Rounds show the narrowest gap among mainstream shapes at 75.6%, partly because lab-grown rounds command a premium over other lab-grown shapes. A lab-grown round still averages nearly $2,000, while lab-grown marquise and radiant cuts sit closer to $1,100. If you're flexible on shape, that's where the best value sits in the lab-grown market right now.

A flood of new inventory

Supply numbers this week were striking. Lab-grown rounds in the 0.30 to 0.49ct range saw inventory jump 511.6%, swelling to 992 listings. Natural round brilliants from 1.00 to 1.24ct surged 418.6% to 414 listings, with 23 new listings appearing and only one delisted. Natural rounds from 1.50 to 1.99ct climbed 225.4% to 209 listings.

Origin	Shape	Carat Range	Listings	Supply Change (7d)
Lab-grown	Round	0.30 to 0.49ct	992	+511.6%
Natural	Round	1.00 to 1.24ct	414	+418.6%
Natural	Round	1.50 to 1.99ct	209	+225.4%
Lab-grown	Round	0.50 to 0.74ct	568	+178.0%
Lab-grown	Oval	1.00 to 1.24ct	135	+127.8%

More supply generally means more competitive pricing, and the natural round brilliant market from 1.00 to 1.99ct is now significantly better stocked than it was a week ago. For anyone shopping for a natural round in the one carat range, this is exactly the kind of week where you'll find both wider selection and more negotiating room. Act before the market absorbs the new inventory and prices stabilise.

Same stone, wildly different price

Shopping around has always mattered with diamonds, but the current cross-retailer spreads show just how much money is on the table. Natural radiants have an average spread of 97.3% between the cheapest and most expensive retailer for equivalent stones. One retailer is charging nearly double what another asks for the same diamond.

Lab-grown ovals show a 53.4% average cross-retailer savings opportunity with an 87.3% spread. Lab-grown marquise cuts carry an 86.6% spread. Even lab-grown rounds, probably the most efficiently priced lab-grown category, have a 74.9% spread between retailers.

These aren't niche categories. Ovals and rounds are the two most popular shapes globally. The price differences are large enough that choosing the wrong retailer can add thousands to your purchase.

On the retailer front, the markup data tells its own story. One small-inventory retailer in our index sits about 114.6% above the cross-retailer median, the highest in our dataset by a significant margin (equivalent stones there cost more than double the cohort median). The largest retailer in our index averages a more moderate 6.4% above median across its ~126k active listings. One value-cohort retailer prices roughly 8.3% below the cohort median on average, making it worth checking for budget-conscious buyers, though its ~1,400 listings mean a smaller selection. Another large US-anchored retailer's ~24,000 active listings all qualify as category price leaders in our tracking.

If you're buying without comparing across retailers, you're probably overpaying. Especially on natural radiants and lab-grown ovals, where your choice of retailer can swing the final price by 80% or more.

Where the real value is this week

Our algorithms flagged several stones priced well below the median for their category. These typically surface when a retailer is running aggressive pricing or a seller wants to move inventory quickly.

Stone	Price	Below Median	Per Carat
Natural Round, M colour, 0.50ct	$143	76%	$286
Natural Oval, I colour, 0.70ct	$340	66%	$486
Natural Radiant, J colour, 0.80ct	$528	63%	$660
Natural Radiant, I colour, 1.00ct	$837	56%	$836
Natural Radiant, M colour, 1.01ct	$1,002	24%	$992

That 0.50ct natural round at $143 is genuinely unusual. A $286 per carat price for a natural round brilliant, even at M colour, sits well below what you'd normally encounter. The two radiants at 0.80ct and 1.00ct also stand out. Natural radiants have been quietly offering some of the best price-to-quality ratios in the market all year, and these listings are particularly sharp examples.

These are snapshot prices. Stones priced this far below the field tend to sell fast. If you're in the market for a natural radiant around one carat, this is a strong week to be looking.

What I'm watching in May

Three things have my attention heading into the new month.

Whether that lab-grown weekly bounce has any staying power. A 5.6% weekly gain against a flat monthly backdrop could be a blip or the early signs of a genuine floor forming. The monthly number needs to shift before I'd call it a trend, but it's the first notable upward move in weeks.

The supply surge in natural rounds. A 400%+ inventory increase in the 1.00 to 1.24ct range is substantial. If that supply persists into May, expect continued downward pressure on natural round prices in the most popular engagement ring category. For buyers, that's excellent. For dealers sitting on stock, less so.

And the ongoing decline in large natural stones with lower colour grades. Pears above 5ct, ovals above 4ct, and cushions above 3ct have all dropped 35 to 48% over the past month. Sustained declines of that magnitude in premium carat weights suggest structural repricing, not weekly volatility. If you've been eyeing a larger natural stone, the market is moving in your favour, and May could push prices lower still.

Whatever you're shopping for right now, compare across retailers before settling on one. With markup spreads this wide and natural prices still sliding, the window for buyers keeps getting better. And when the same one carat radiant can cost $837 at one retailer and twice that at another, where you buy matters just as much as what you buy.