How Lab-Grown Diamonds Are Letting Buyers Upgrade to Larger Stones in 2026

Lab-grown diamonds are produced in a controlled laboratory environment — either via Chemical Vapour Deposition (CVD) or High Pressure High Temperature (HPHT) — and are chemically, physically, and optically identical to mined diamonds. In 2025 and 2026, that definition has started to carry a very practical consequence for engagement ring buyers: Harmony Jewels, a Hatton Garden retailer, reported that its mean centre stone weight climbed above 2 carats, with demand for exact 3ct stones nearly doubling year on year — a shift the retailer attributes directly to the affordability of lab-grown diamonds.

For Indian buyers, where the average household approaches a diamond engagement ring with a budget that has historically capped out well below what a 2ct mined stone would cost, this is not a minor trend. It is a structural change in what is actually purchasable.

How Do Lab-Grown Diamond Prices Compare to Mined Diamonds by Carat Size?

The price gap between lab-grown and mined diamonds is the engine behind everything Harmony Jewels' data shows. The table below maps approximate price points across three carat weights, using the trajectory reported by market data cited in the Financial Times and tracked by analysts including Edahn Golan.

Carat Weight	Approx. Mined Diamond Price (2026)	Approx. Lab-Grown Diamond Price (2026)	Lab-Grown Discount vs. Mined
1ct round, VS2/G	~$5,000–$7,000	~$768	~85–90%
2ct round, VS2/G	~$18,000–$25,000	~$2,500–$3,500	~85–88%
3ct round, VS2/G	~$40,000–$60,000	~$5,000–$8,000	~85–90%

Sources: Alyce Jewels citing Financial Times/Tenoris data; JCK/Tenoris Q1 2026 wholesale price analysis. Mined diamond prices are indicative and vary significantly by cut grade, fluorescence, and market.

The headline figure: the average retail price of a one-carat round lab-grown diamond declined 79% to $768 between January 2020 and May 2026, per Tenoris data reported by the Financial Times. That single data point reframes the entire conversation about what a "realistic" engagement ring looks like.

An Indian buyer working with a budget of, say, ₹3–5 lakh (roughly $3,600–$6,000 at current exchange rates) would have found a 1ct mined diamond a stretch even a few years ago. Today, that same budget can reach a 2ct or even a 3ct lab-grown stone with room left for a quality setting.

What Does the Harmony Jewels Data Actually Tell Us?

Harmony Jewels reported that its mean centre stone weight rose above 2ct during 2025, and that demand for exact 3ct stones nearly doubled year on year. The retailer, based in Hatton Garden — London's historic jewellery quarter — serves a customer base that skews toward considered, research-driven purchases rather than impulse buys.

The 3ct data point is worth dwelling on. Three carats is not a "slightly bigger" stone; it is a size that, in mined diamonds, would price out the overwhelming majority of engagement ring buyers globally. Demand for that specific weight nearly doubling in a single year at a single retailer suggests that lab-grown pricing has crossed a psychological threshold — buyers are no longer treating 3ct as aspirational but as achievable.

This pattern is consistent with broader US data. Tenoris data cited by the Financial Times shows laboratory-grown diamonds represented 57% of engagement rings sold by units in the United States between January and May 2026 — up from just 10% in 2020. The shift from 10% to 57% in six years is one of the fastest category transitions in modern retail jewellery history.

Why Are Lab-Grown Diamond Prices Falling So Fast?

Lab-grown diamond price erosion is not a temporary correction — it is the predictable result of a technology-driven supply curve, with expanding manufacturing capacity outpacing consumer demand growth.

Wholesale prices for lab-grown diamonds declined 14% in the first quarter of 2026 alone, with no clear floor yet identified, according to analyst Edahn Golan. The sharpest drops are at the larger end: 3ct round lab-grown diamonds fell 28% in Q1 2026, versus 15% for 1ct rounds.

India is central to this supply story. India's polished lab-grown diamond exports overtook natural diamonds in volume for the first time in FY 2025-26, with 18.8 million carats of polished lab-grown diamonds exported versus 16 million carats of cut and polished natural diamonds. A decade ago, the comparison was not even close: in 2015-16, India exported 33.51 million carats of natural diamonds and just 100,000 carats of lab-grown stones.

Surat, the world's dominant diamond cutting and polishing centre for decades, has pivoted aggressively toward CVD manufacturing. Estimates put the number of active CVD reactors in India at around 2,500, predominantly in Surat, with capacity to grow certified diamonds from 0.5 to 5 carats. That manufacturing depth is what makes the price declines structural rather than cyclical.

In value terms, the picture is more nuanced. The average export price of natural diamonds is about $760 per carat, compared to $60 per carat for polished lab-grown diamonds. That gap means India's lab-grown export volumes are not yet translating into equivalent revenue — but for the Indian buyer on the receiving end of those stones in finished jewellery, the per-carat price differential is precisely the point.

What Does This Mean for Indian Engagement Ring Budgets Specifically?

The Indian engagement ring market operates under a set of constraints that differ meaningfully from Western markets: family involvement in purchase decisions, an emphasis on visible size and presence (a stone that "shows" well in photos and at ceremonies), and budgets that are often fixed well in advance of the purchase.

Lab-grown diamonds address each of these constraints simultaneously. A buyer who previously had to choose between a 0.5ct mined stone and a 1ct lab-grown stone at the same price point can now, in 2026, consider a 1.5ct or 2ct lab-grown stone at that same budget. The Harmony Jewels data suggests this is exactly what is happening — buyers are not pocketing the savings; they are trading up in size.

Lab-grown engagement ring sales at US independent retailers were up 41% in January 2026, with units sold increasing 34% and average retail price rising just 5%. Volume up sharply, price barely moving — that is the signature of a market where buyers are choosing larger stones rather than paying more per carat. Indian buyers are navigating the same dynamic.

For a practical illustration: a ₹2.5 lakh budget (approximately $3,000) in 2020 might have reached a 0.7–0.8ct lab-grown stone. In 2026, that same budget can reach a 1.5–2ct lab-grown diamond with a VS2/G grading from IGI. That is not a marginal improvement — it is a generational shift in what the category delivers per rupee spent.

How Does IGI Certification Fit Into the Indian Lab-Grown Diamond Market?

IGI — the International Gemological Institute — is the world's largest independent gemological laboratory, with a particular concentration in lab-grown diamond grading. For Indian buyers, IGI certification is the primary quality assurance mechanism for lab-grown diamond purchases, functioning as the equivalent of what GIA certification does for mined diamonds in Western markets.

IGI reported 21% year-on-year growth in both revenue and EBITDA for the quarter ended March 2026, with consolidated revenue of Rs 3,686 million versus Rs 3,048 million in the same period the prior year. Profit after tax rose 28% year-on-year to Rs 1,796 million. For the 15-month period from January 2025 to March 2026, IGI recorded revenue of Rs 15,976 million, up 18% year-on-year, with EBITDA margins of 60.9%.

Those numbers matter for buyers because they signal that the certification infrastructure is scaling alongside manufacturing. A market where stones are being produced faster than they can be certified would create quality assurance gaps; IGI's growth suggests the opposite — the grading pipeline is keeping pace with supply.

IGI currently operates 36 laboratories and 21 Schools of Gemology across 10 countries, with a strong presence in India. For an Indian buyer purchasing a 2ct or 3ct lab-grown stone, an IGI certificate provides the cut, colour, clarity, and carat weight verification that makes the purchase defensible — both personally and within the family context that often surrounds Indian engagement ring decisions.

Should Indian Buyers Be Concerned About Lab-Grown Diamond Resale Value?

This question comes up in almost every serious conversation about lab-grown diamonds in India, and it deserves a direct answer: lab-grown diamonds have limited and declining resale value, and that trajectory is likely to continue.

The inventory-to-sales ratio for lab-grown diamonds has risen from "the high single digits" in 2020 to nearly 50% at present, according to Tenoris. Sell-through has slowed, and stones are remaining in inventory longer. For retailers, this creates capital pressure. For buyers thinking about resale, it means the secondary market for lab-grown diamonds is thin and likely to stay that way.

A lab-grown diamond engagement ring is a consumption purchase, not an investment. The value it delivers is in the experience of wearing it, the size and quality of the stone relative to what the same budget would buy in mined diamonds, and the emotional significance of the occasion it marks. It is not a store of value in the way that gold jewellery has traditionally functioned in Indian households.

If resale value is a primary concern, gold weight in the setting and the quality of the metalwork become more important than the stone itself. Many Indian buyers are navigating this by choosing lab-grown stones for the centre diamond — where size and visual impact matter most — while retaining gold settings that carry their own intrinsic value.

What Carat Sizes Are Most Popular Among Indian Lab-Grown Diamond Buyers in 2026?

The Harmony Jewels data points to a clear direction: buyers are gravitating toward sizes that would have been inaccessible in mined diamonds. The mean above 2ct and the near-doubling of 3ct demand are the headline figures, but the underlying dynamic is a general shift upward across the size distribution.

For Indian buyers specifically, the most active segments appear to be:

1ct to 1.5ct: The entry point for buyers who previously considered 0.5ct to be the realistic ceiling. At current lab-grown prices, a 1ct round VS2/G stone can be sourced for well under ₹1 lakh, making this the new "standard" for mid-range Indian engagement rings.

1.5ct to 2ct: The sweet spot for buyers with budgets in the ₹1.5–3 lakh range. Our guide to 1.5 to 2 carat oval lab-grown diamond solitaire rings in India covers this segment in detail, including setting options and what to look for in cut quality at this weight.

2ct to 3ct: Increasingly accessible for buyers with budgets above ₹3 lakh. This is where the most dramatic shift appears to be occurring — buyers who would previously have topped out at 1ct mined are now reaching 2–3ct lab-grown.

Above 3ct: Still a niche segment in India, but no longer purely aspirational. With 3ct lab-grown rounds available for under $8,000 wholesale, retail prices in India for certified 3ct stones are within reach for buyers at the premium end of the market.

How Does the CVD vs. HPHT Choice Affect Indian Buyers at Larger Carat Weights?

CVD (Chemical Vapour Deposition) places a diamond seed crystal in a chamber filled with carbon-rich gas, which is then ionised to deposit carbon atoms onto the seed, growing a diamond layer by layer. HPHT (High Pressure High Temperature) replicates the geological conditions under which natural diamonds form, using extreme pressure and heat to crystallise carbon around a seed.

For Indian buyers, the CVD/HPHT distinction matters more at larger carat weights. At 1ct and below, both processes produce stones that are difficult to distinguish without specialist equipment. At 2ct and above, the differences in growth characteristics become more relevant.

CVD stones at larger sizes can sometimes show graining or strain patterns that affect transparency. Quality control is therefore more variable at the top of the size range, making certification and cut grade more important, not less. HPHT stones at larger sizes tend to have more consistent colour distribution, but the process is more energy-intensive and the cost advantage over CVD narrows at very large sizes.

India exports mainly CVD diamonds, with most HPHT rough used for jewellery manufacturing imported from China. For an Indian buyer purchasing a 2ct or 3ct stone, asking specifically whether the stone is CVD or HPHT — and checking the IGI certificate for any notation on growth method — is a reasonable due diligence step.

What Should Indian Buyers Actually Do With This Information?

The Harmony Jewels data, the Tenoris price analysis, and the Indian export figures all point in the same direction: the lab-grown diamond market in 2026 is delivering genuine size upgrades at realistic price points, and that trend is not reversing in the near term.

For Indian buyers, the practical implications break down as follows.

Set your budget first, then choose your size. The old approach of deciding on a carat weight and then finding the budget to match it is now backwards. With lab-grown prices continuing to fall, starting from a fixed budget and asking what size that budget reaches today — rather than what it reached two years ago — will consistently yield a larger stone.

Prioritise cut grade over colour and clarity at larger sizes. A 2ct lab-grown stone with an Excellent cut grade will outperform a 2.5ct stone with a Very Good cut in terms of visual impact. At larger sizes, the difference between cut grades becomes more visible, not less.

Get IGI certification for any stone above 1ct. The certification cost is marginal relative to the purchase price, and it provides documentation that makes the purchase verifiable — important for personal confidence and for any future insurance or resale scenario.

Consider the setting as a long-term investment. Since the stone itself carries limited resale value, the quality of the gold setting, the craftsmanship of the prongs, and the durability of the metalwork matter more than they would in a mined diamond purchase. Our guide to the best lab-grown diamond engagement rings in India covers setting options across budgets.

Don't assume the price you see today will be lower next year. While wholesale prices have been falling, retail prices in India are influenced by import duties, GST, and retailer margins that don't move in lockstep with international wholesale trends. Waiting for prices to fall further is a reasonable strategy in some markets; in India, the tax and duty structure means the savings from further wholesale price declines may not fully pass through to consumers.

The Harmony Jewels data confirms something Indian buyers have been discovering independently: the lab-grown diamond market has crossed a threshold where larger stones are not just theoretically affordable but practically purchasable. The mean above 2ct and the near-doubling of 3ct demand are not outliers — they are the leading edge of a shift already visible in Indian jewellery stores, online platforms, and the conversations happening in families planning engagements in 2026.