Lab-Grown Supply Surged 66% and Prices Rose Anyway

Lab-grown diamonds outnumbered natural stones by more than three to one in the week ending April 13. That ratio alone wasn't news. What made this week notable: lab-grown supply surged 66% in seven days while natural inventory contracted 15%, and lab-grown prices still went up. For a product that can be manufactured on demand, the usual supply and demand playbook clearly doesn't apply the way you'd expect.

The numbers were stark. Nearly 1.85 million lab-grown diamonds were actively listed across tracked retailers, against just 571,000 natural stones. Total active inventory across the market hit 27.1 million observed price points, up 6% from the prior period and marking the seventh consecutive period of growth. The diamond market, at least the visible and trackable portion of it, kept getting bigger. And lab-grown was driving virtually all of that expansion.

Two markets, opposite trajectories

Natural diamond supply was thinning, with listings falling from roughly 668,000 to 571,000. Lab-grown went the other direction entirely, expanding from about 1.1 million listings to 1.84 million. An additional 730,000 stones entered the tracked market in a single week.

Prices moved against what you'd predict. Lab-grown average prices climbed 18.4% to $856, most likely driven by a richer mix of higher carat stones entering through expanded retailer coverage. Natural diamonds drifted down 1.8% to $1,503.

Metric	Natural	Lab-Grown
Active listings	571,138	1,842,891
Average price	$1,503	$856
7 day price change	down 1.8%	up 18.4%
7 day supply change	down 14.5%	up 65.9%
Delisted in 7 days	297,642	574,418

The 43% price gap between lab-grown and natural held remarkably steady despite these supply swings. A lab-grown diamond cost roughly 57 cents on the dollar compared to its natural equivalent. In practical terms, a natural 1ct round brilliant in the G colour, VS2 clarity range typically listed around $4,500 to $6,000 depending on cut quality and retailer. The lab-grown equivalent sat closer to $800 to $1,200. That's not a discount. That's a fundamentally different price tier.

And the gap had been widening. A year earlier, the typical lab-grown discount hovered around 30 to 35%. At 43%, the two product categories were behaving less like alternatives and more like separate markets entirely.

Where shapes split apart

Not all shapes moved together. Princess, emerald, and asscher cuts posted substantial gains while ovals and trillions dropped sharply. The divergence was significant enough to matter for anyone shopping a specific shape during this window.

Shape	Listings	Median Price/ct	7 Day Change
Princess	78,351	$1,000	up 71.2%
Emerald	186,338	$1,219	up 46.0%
Asscher	32,102	$1,402	up 19.0%
Oval	446,099	$900	down 23.5%
Trillion	1,005	$776	down 21.3%

Princess cuts jumped over 70% in median price per carat. That's a dramatic move, and it almost certainly reflected a composition shift rather than pure price inflation. When a wave of higher quality princess cuts enters the market (particularly lab-grown stones with excellent cut grades), the median gets pulled up even if individual stone prices stay flat. Buyers shopping princess cuts should always have been checking actual asking prices on specific stones rather than taking aggregate medians at face value.

Ovals told the opposite story. As the most popular fancy shape, ovals were already abundantly supplied, and the fresh lab-grown inventory pushed median prices down 23.5%. That made the week ending April 13 a particularly good window for oval shoppers. More supply, lower prices, and a deep enough market that finding a well-cut stone with strong scores required no heroics.

Emerald cuts deserved particular attention. With 186,000 listings and a 46% price increase, this shape was experiencing genuine demand pressure. Emerald cuts have been trending upward for months, driven partly by social media visibility and partly by buyers discovering that step cuts show fewer inclusions than brilliant cuts at the same clarity grade. A VS2 emerald cut can look completely eye-clean at a fraction of what you'd pay for a comparable round. That value proposition was pulling more buyers toward the shape, and the pricing showed it.

Shape preferences have always cycled, but those cycles have accelerated in the lab-grown era. When a shape trends, manufacturers can ramp production within weeks. Natural supply can't respond that fast. The result is wider price swings in lab-grown shapes and better opportunities for buyers who aren't chasing whatever's trending right now.

The 90% retailer spread hiding in plain sight

The most actionable number in the entire dataset: the median cross-retailer spread sat at 89.8%. When the same certified diamond appeared at multiple retailers (and 47.6% of all certified stones did), the price difference between the cheapest and most expensive listing was nearly 90%.

Same physical stone. Same certificate number. Same lab report. One retailer charging almost double another.

For lab-grown diamonds specifically, cross-retailer spreads tend to run even wider than natural. Manufacturing economics allow for enormous margin variability. One retailer might source directly from a grower at cost plus 15%, while another buys through two intermediaries and adds a 60% retail margin. Identical stone. Very different price.

This is why comparing across retailers matters more than almost any other decision in the buying process. You can spend hours optimising for colour grade or clarity, save $200 by stepping down from VS2 to SI1, and then lose $2,000 by failing to check whether the same stone exists cheaper elsewhere. That 90% median spread made retailer selection the single highest leverage decision for any buyer, lab-grown or natural.

The 47.6% overlap rate itself was climbing steadily, up 7.9% across the measurement window. An increasing proportion of the market was becoming directly comparable, stone for stone. For informed buyers, that was welcome news. For retailers banking on the assumption that customers wouldn't shop around, it was a growing problem. The market was becoming more transparent whether retailers wanted it to or not.

What the supply surge signalled

The raw supply numbers told only part of the story. Underneath the headline 66% lab-grown surge, several other indicators shifted in ways that mattered for price discovery.

Signal	Movement	Detail
Off market listings	down 77.6%	3.9M to 872K stones pulled from sale
New listings	up 35.7%	2.4M vs 1.8M in prior period
Active inventory	up 6.0%	Seventh consecutive period of growth
Cross-retailer overlap	up 7.9%	Rising across 7 measurement periods

Retailers were aggressively listing inventory and keeping it active rather than cycling stones on and off the market. The 77.6% drop in off market listings was particularly telling. Fewer stones were being pulled from sale, which meant effective available supply was even larger than the headline count suggested.

For lab-grown buyers, the practical implication was straightforward. More choice than ever, but more homework required too. Sorting through 1.8 million options to find genuine value meant filtering for the right specifications first, then verifying whether the same stone existed cheaper at a competing retailer. The tools for that comparison existed. Using them was the difference between a fair deal and overpaying by thousands.

Lab-grown quality wasn't the weak point

A persistent myth about lab-grown diamonds is that they sacrifice quality for price. The data from this period didn't support that claim. Lab-grown stones routinely scored well on cut, polish, and symmetry, often matching or exceeding natural equivalents in the same carat range. Manufacturing allows tighter control over proportions and finish than geological formation ever could.

Where quality differences did show up was in certification. Many lab-grown diamonds carried IGI certificates rather than GIA, and the grading standards between labs aren't identical. A GIA certified lab-grown diamond at any given grade is generally a more conservative call than an IGI equivalent, though the premium for GIA certification could add 10 to 20% depending on the retailer.

For buyers prioritising quality over price, the CaratHunter scoring system accounted for these certification differences. A lab-grown diamond with an excellent quality score had genuinely excellent proportions, polish, and symmetry regardless of which lab issued the certificate. The score cut through the certification noise.

What lab-grown shoppers should have been doing

The week's data pointed to a few specific strategies.

Ovals were the strongest value play. Median prices fell 23.5%, supply was abundant, and buyers had real negotiating power. An oval lab-grown diamond in the 1 to 2 carat range, F to H colour, VS1 to VS2 clarity, offered the best price-to-quality ratio in the market during this window.

Step cuts (emerald, asscher) were the opposite. Rising prices and building demand meant less room to negotiate. Buyers set on an emerald cut would have done well to act quickly rather than waiting for price drops that weren't coming.

Princess cuts required scepticism. The 71% median price surge looked alarming, but it was almost certainly compositional. Individual princess cut lab-grown diamonds were still available at competitive prices. The aggregate number was misleading. Always check the stone, not the statistic.

And regardless of shape, every buyer should have been running cross-retailer comparisons. With a 90% median spread, the retailer mattered more than the colour grade, more than the clarity, more than almost any gemological specification. Two minutes of comparison shopping could save more than weeks of spec optimisation.

Where this was headed

The supply trajectory was clear: lab-grown inventory would keep growing. Manufacturing capacity continued expanding, particularly from Indian producers who dominated the market for stones under 2 carats. Whether prices would follow supply down or stabilise depended on how aggressively retailers competed on price versus protecting margins.

Natural diamonds faced a different question. Supply had contracted 15% in a single week, suggesting either tightening at the mining level or retailers consolidating inventory positions. If that trend continued, natural prices had room to firm up, which would push the gap with lab-grown wider still.

What wouldn't change anytime soon was the fundamental value equation. Lab-grown offered the same visual, physical, and chemical properties as natural at roughly half the price or better. The tradeoff was resale value, which for lab-grown remained near zero. Natural diamonds retained some secondary market value, though far less than the industry has historically implied. For buyers focused on wearing a beautiful stone rather than holding an asset, lab-grown remained the rational choice.

The cross-retailer overlap trend was the one worth watching most closely. As more retailers listed the same stones, price transparency should improve and the extreme spreads should narrow. Should. But many buyers still don't compare, which means the 90% median spread could persist longer than economics alone would predict.

For buyers in that window, the guidance was simple: buy lab-grown for the stone, not the investment. Compare across retailers before committing to anything. And if you're flexible on shape, follow the value. In the week ending April 13, that value was sitting squarely in the oval market. Wherever it moves next, the data will show it.