The Largest Lab-Grown Diamond Manufacturers in India (2026)

Key takeaways

• KIRA has the strongest public scale evidence in the reviewed Indian manufacturer set: 4,000 CVD reactors and more than 250,000 polished carats per month reported by GJEPC.
• Public producer figures use incompatible units-reactors, polished carats, polished stones, or a single large-stone record-so this is an evidence-ranked comparison, not an audited league table.
• Greenlab also makes a large CVD claim, but its public 1,000-reactor figure is a company disclosure rather than an independently comparable production measure.
• For calibrated layouts, matched pairs, and custom cuts, technical fit and repeatability can matter more than maximum factory volume.

How to read "largest"

There is no complete public census of Indian gem-quality laboratory-grown production. A reactor count is not the same as polished carats per month, and polished-stone capacity cannot be compared directly with carat capacity. A responsible ranking therefore reports what each producer has publicly disclosed, labels the unit, and avoids converting unlike measures into a false precision.

The table below uses the strongest public evidence located in the fact base. "Not disclosed" means that a comparable current number was not established in the reviewed sources; it does not mean the producer has no capacity.

Public-evidence comparison

Evidence: Verified public evidence

Producer	Public capacity evidence	Certification or quality evidence	Specialization	HQ / production	Source
KIRA / Kira Jewels	4,000 CVD reactors; over 250,000 polished ct/month reported by GJEPC; 350,000 polished ct/month described by JCK as planned capacity	SMETA and SEDEX reported by GJEPC; certified inventory emphasized	Integrated grow–cut–polish–jewellery; broad inventory, larger sizes, fancy shapes	Surat, India	GJEPC; JCK [1] [2]
Greenlab Diamonds	1,000 reactors and 2,000 employees in company LinkedIn materials	Company materials cite IGI and GIA certification; Type IIa positioning	CVD cultivation, colourless and specialty stones, B2B supply	Surat, India; Belgium described as head office	Company materials 3
Diamond Foundry	Spain expansion expected to reach 4–5 million carats/year as reactors are commissioned	Producer positioning; exact certification mix not established in the reviewed evidence	Large-scale CVD; jewellery and technology applications	United States; Spain expansion	Spain investment agency 4
IIa Technologies	Historical disclosure of 50+ MPCVD reactors; earlier trade reporting cited more than 300,000 ct/year	Type IIa specialization associated with the company	CVD, Type IIa, large and high-quality diamonds	Singapore	Trade reports 5
Bhanderi Lab Grown Diamonds	2M+ diamond polishing capacity; unit is individual stones, not carats/year	Company emphasizes Type IIa and CVD; current certification mix not independently established	CVD, Type IIa, large-scale polishing and export	Surat, India	Company materials 6
Elmonas Diamonds	Capacity confirmed at quotation; 12,209 certified stones available to order	IGI or GIA; grades, fluorescence and cut stated per stone	CVD and HPHT; calibrated layouts, matched pairs and custom cuts; tolerance ±0.05mm on diameter/length-width	Own benches in Surat, India	Elmonas process; stock 1 to 5 working days, bespoke 5 to 10 working days; advance, LC or memo terms confirmed with each quote
Ethereal Green Diamond	Current public capacity not disclosed	IGI-graded 75.33 ct "Celebration of India" and 30.69 ct "Infinity Ring"	Large, high-quality CVD, large stones, specialty cuts	Surat, India	IGI 7

Who is the biggest producer?

Evidence: Verified public evidence

If "biggest" means the strongest publicly stated current Indian production figure, KIRA is the defensible answer in this source set. GJEPC reported expansion from 2,600 to 4,000 CVD reactors and over 250,000 polished carats per month. JCK's 350,000 polished-carat figure should be labelled planned capacity, not current output.1 2

That answer is narrower than saying KIRA is best for every buyer. A factory built for scale may be appropriate for standardized volume, broad inventory, or large recurring programmes. It does not automatically establish the tightest dimensional tolerance, the best matched-pair process, or the fastest response to an unusual CAD-driven cut. Those are different buying questions.

Who is the leading supplier?

Evidence: Verified public evidence

Where Elmonas fits

Evidence: Elmonas process

Elmonas focuses on specification-led work for calibrated layouts, matched pairs, and custom cuts where the buyer needs the design requirement translated into a clear sourcing and QC brief. Elmonas states its working figures rather than a capacity claim: calibrated work holds a tolerance of plus or minus 0.05mm on diameter and length-width, ex-stock stones ship in 1 to 5 working days with bespoke and cut-to-order work at 5 to 10 working days, and there is no minimum order for stones 2 carats and above (10 carats total minimum when individual stones are below 2 carats). Capacity figures are confirmed at quotation. For a direct trade conversation, see Elmonas trade supply.

A buyer's ranking method

Before selecting a manufacturer, decide whether the requirement is commodity volume, an unusual shape, a matched pair, a calibrated layout, a specialty colour, a large centre stone, or a repeat collection. Then compare suppliers on the unit that matters: polished carats, individual stones, available inventory, dimensional tolerance, report format, lead time, or service region. This prevents a large reactor count from answering a question it was never designed to answer.

For calibrated and design-specific requirements, see calibrated diamond layouts, matched pair diamonds, and custom-cut diamonds.