Lab-grown diamonds are real diamonds. That is a fact supported by every major gemological institution in the world.
But the market also contains sellers who use the lab-grown diamond label to sell something that is not a diamond at all. Moissanite. Cubic zirconia. White sapphire. Glass. These are diamond simulants, not diamonds, and they are sold by dishonest sellers as lab-grown diamonds to buyers who do not know the difference.
This guide gives you every verification tool and red flag you need to protect yourself before you spend money on what should be a certified diamond piece.
What Fake Lab-Grown Diamonds Actually Are
A genuine lab-grown diamond is composed of pure carbon in a cubic crystal structure, identical to a mined diamond. It has a Mohs hardness of 10, a refractive index of 2.417 to 2.419, and specific gravity of 3.52. These properties cannot be faked by any other material currently in use in the jewellery market.
What dishonest sellers attempt to pass off as lab-grown diamonds are diamond simulants: materials that look similar to diamond from a distance but have different physical and optical properties. The most common simulants in India are:
Moissanite: Silicon carbide with a hardness of 9.25 and a higher refractive index than diamond (2.65 to 2.69). It creates a rainbow or disco-ball sparkle effect not seen in genuine diamonds. Moissanite is a legitimate gemstone in its own right and is sold honestly by many Indian retailers. The fraud occurs when it is sold as a lab-grown diamond rather than as moissanite.
Cubic Zirconia (CZ): A synthetic zirconium dioxide with a hardness of 8 to 8.5. Much softer than diamond and visibly different in sparkle pattern under magnification. CZ is the lowest-cost diamond simulant and the most commonly used in fraudulent sales of very cheap supposed lab-grown diamond pieces.
White Sapphire: A natural or synthetic corundum with a hardness of 9. Less brilliant than diamond with a milkier, less crisp sparkle. Used in higher-end simulant fraud.
Glass: The least sophisticated simulant. Hardness of approximately 5.5. Visible scratches after short wearing periods.
Ten Red Flags That Should Stop a Purchase Immediately
Red Flag 1: No IGI Certificate or Unverifiable Report Number
A genuine certified lab-grown diamond always comes with an IGI, GIA, or SGL certificate containing a unique report number. If the seller cannot provide this number before purchase, or if the number entered at report.igi.org returns no result or a result that does not match the stone described, stop the purchase immediately.
Some fraudulent sellers show certificate images without providing the actual report number for independent verification. An image of a certificate is not a certificate. Always verify the report number yourself.
Red Flag 2: Price That Is Significantly Below Market Rate
A 0.50 carat round brilliant lab-grown diamond in G colour and VS2 clarity with an Excellent cut, set in 14K gold, costs approximately Rs 28,000 to Rs 45,000 from a reputable Indian retailer in 2026. If you are being offered an apparently equivalent piece for Rs 8,000 to Rs 12,000, the stone is not a diamond.
Lab-grown diamonds are significantly less expensive than mined diamonds. But they are not as cheap as moissanite or CZ. If the price seems impossible, the product is not what it claims to be.
Red Flag 3: Rainbow or Disco-Ball Sparkle
A genuine round brilliant diamond produces white and coloured light in a balanced pattern called brilliance and fire. Moissanite, which is the most common simulant used in lab-grown diamond fraud, produces significantly more coloured fire than a genuine diamond. In direct light, moissanite creates a rainbow or disco-ball effect that is visually distinctive from the sparkle of a genuine diamond.
If a stone produces strong rainbow flashes that look more colourful than white, it is almost certainly moissanite. Genuine diamond sparkle includes coloured flashes but they are balanced with white light.
Red Flag 4: Seller Cannot Name the Certification Body
A genuine lab-grown diamond piece is certified by IGI, GIA, or SGL. These are the three major certification bodies whose reports are accepted in the Indian market. If a seller says the diamond is certified but cannot name the specific certification body or provide the certificate, there is no genuine certification.
Red Flag 5: No BIS Hallmark on the Gold Setting
A fraudulent diamond is often paired with a fraudulent gold claim. Always check the BIS hallmark stamp on the gold setting. The hallmark is stamped on the inside of ring bands, the back of pendants, the post of earrings, or the clasp of bracelets. If there is no BIS hallmark, the gold purity claim is unverified.
Red Flag 6: Seller Discourages Independent Verification
A reputable seller actively encourages you to verify the IGI certificate before purchasing. A fraudulent seller will discourage this by saying the certificate is inside the sealed package, that verification takes too long, or that their word is sufficient. Any resistance to independent certification verification before purchase is a serious warning signal.
Red Flag 7: No Physical Store or Verifiable Address
Online-only sellers without any verifiable physical presence are a higher fraud risk category. A seller who cannot provide a physical address, who has no Google reviews, and whose website was registered recently is demonstrating multiple risk factors simultaneously.
Red Flag 8: The Stone Appears Too Perfect
Genuine lab-grown diamonds, like mined diamonds, have natural inclusions visible under 10x magnification. A stone that appears completely flawless under a jeweller loupe at a price point below Rs 50,000 per carat is either a very high-grade diamond (which would be priced accordingly) or a simulant. CZ and moissanite, being synthetic materials engineered for optical appearance, often appear eye-clean and inclusion-free in ways that mid-grade diamonds do not.
Red Flag 9: Heat Conductivity Difference
Diamond conducts heat exceptionally well. Simulants do not. A diamond thermal tester, available at most reputable jewellers and from online retailers for Rs 2,000 to Rs 5,000, distinguishes diamond from CZ, glass, and white sapphire with high accuracy. Note: moissanite also conducts heat similarly to diamond and requires a more sophisticated moissanite-specific tester to distinguish.
If you are making a significant purchase from an unfamiliar seller, requesting a thermal test at the point of sale is entirely reasonable.
Red Flag 10: Pressure to Buy Immediately
A seller who creates artificial urgency, today only price, limited stock, price goes up tomorrow, is using a high-pressure sales technique that has no place in a genuine fine jewellery sale. A reputable jeweller selling a verified certified piece has no reason to rush your decision.
How to Verify a Lab-Grown Diamond Before Purchase: The Three-Step Process
Step 1: Request the IGI report number before agreeing to purchase. Enter it at report.igi.org. Confirm that the result matches: the stone is described as laboratory-grown, the 4Cs match the seller description, and the report is not flagged as withdrawn or cancelled.
Step 2: Ask to examine the stone under good light and observe the sparkle pattern. If you have access to a jeweller loupe (10x magnification), examine the stone for natural inclusions that confirm it is not a perfectly engineered simulant.
Step 3: Check the BIS hallmark on the gold setting physically after delivery.
What to Do If You Suspect You Have Been Sold a Fake
If you have received a piece and suspect the stone is not a genuine diamond, take it to any reputable jeweller for a diamond thermal test. If the test is negative, you have grounds for a return.
File a complaint with the National Consumer Disputes Redressal Commission (NCDRC) if the seller refuses a return for a misrepresented product. Keep all purchase documentation, including the product listing, any certificate images provided by the seller, and your payment confirmation.
If payment was made by credit card, initiate a chargeback dispute with your bank citing misrepresentation of the product.
Frequently Asked Questions
Can a jeweller tell a lab-grown diamond from a mined diamond visually?
No. Lab-grown diamonds and mined diamonds are physically and chemically identical. Even an experienced gemologist with a loupe cannot visually distinguish them. Only advanced spectroscopic equipment can identify the growth method. This is why the IGI certificate, which records whether a stone is laboratory-grown or natural, is essential documentation.
Is moissanite a fake diamond?
Moissanite is not a fake diamond when sold as moissanite. It is a legitimate gemstone with its own properties and beauty. It becomes fraud only when sold as a lab-grown diamond at a lab-grown diamond price. Ask explicitly whether a stone is a diamond or moissanite before purchasing.
What is the most reliable way to avoid being sold a fake lab-grown diamond in India?
Buy from retailers with physical stores, verifiable IGI certificates with report numbers you check independently at report.igi.org, BIS hallmarked gold, and a documented buyback policy. Goenka Jewellers meets all of these criteria for every piece in their collection.
Does an expensive price guarantee a real diamond?
No. Price alone does not guarantee authenticity. A fraudulent seller may price a simulant at a level that mimics the discount relative to mined diamonds to appear credible. The IGI certificate verification is the only reliable guarantee.
The Bottom Line
The lab-grown diamond market in India is overwhelmingly populated by genuine, certified retailers selling real diamonds. The fraud risk is real but avoidable with the right verification habits.
Verify the IGI report number before purchase. Check the BIS hallmark after delivery. Buy from retailers with physical presence and documented policies. Those three habits eliminate the vast majority of lab-grown diamond fraud risk in India.
For the complete online buying safety checklist, read our How to Buy Diamond Jewellery Online Safely in India: A 10-Point Checklist. For certification guidance, read our IGI Certified Lab-Grown Diamonds: Why Certification Matters in India. Then explore the complete certified lab-grown diamond collection at Goenka Jewellers