18 Carat Hallmark Gold: What the 750 Stamp Means

Turn a diamond ring over and a tiny number usually hides inside the band. 750. That stamp is the heart of the 18 carat hallmark: a BIS certification that the metal is 75% pure gold, 18 parts in 24, the standard purity for diamond and stone-set jewellery across India and much of the world. The number is small. What it settles is not: purity disputes at resale, exchange arguments, and the assay conversation whenever the piece backs a Gold Loan with a lender such as IIFL Finance. This guide decodes the full hallmark on 18 carat gold, shows how to verify it at home in a minute, explains why diamond jewellery lives at this purity, and covers what 750 means in rupees when the gold is valued.

What Does an 18 Carat Hallmark Mean?

Carats count gold in twenty-fourths. Eighteen parts gold, six parts alloy, gives 18 carat, which is 75% purity, written in fineness terms as 750, meaning 750 parts per thousand. The BIS hallmark is the government-backed certification of exactly that number. An assaying centre tests the piece, and the mark it applies is legal confirmation, not a jeweller's claim. So a 750 stamp inside a hallmarked ring is not decoration. It is the difference between purity you can prove and purity you were told.

The Components of the BIS Hallmark on 18 Carat Gold

Since 2021, the hallmark has three components, and all three should be present together:

• The BIS logo. The standing triangle, the certification body's own mark.
• The purity grade. For 18 carat, the stamp reads 18K750, tying the carat and fineness together in one mark.
• The HUID. A six-character alphanumeric code unique to that one piece, registered in the BIS database.

Older jewellery hallmarked before the 2021 change carries a larger set of marks, including the assaying centre's and jeweller's identification. Those pieces are genuine. But jewellers must have old-format stock re-hallmarked into the current system before reselling it, so the three-mark format is what new purchases should always show.

How to Verify an 18 Carat Hallmark at Home

Three steps, one phone. Find the marks, usually inside a band, on a clasp, or the back of a pendant, and a magnifying glass helps since the stamps are tiny. Read them: triangle, 18K750, and the six-character code. Then open the BIS CARE app, enter the HUID, and the piece's registered details appear, purity, article type, hallmarking particulars. A match means the stamp is genuine. No result, or details that contradict the piece in your hand, is reason to go back to the seller with questions. The whole check takes under two minutes and costs nothing.

Why Diamond Jewellery Uses 18 Carat (750) Gold

Diamond settings need metal that holds a shape. Pure gold does not; it bends under a fingernail's determination, and 22 carat is not much sterner. At 75% gold and 25% alloy, 750 metal is hard enough for prongs to grip a stone through daily wear, yet still rich enough in gold to look and feel premium. It also alloys cleanly into white and rose shades, which diamond design leans on heavily. So the pairing is engineering, not fashion. The stone needs claws that do not loosen. 18 carat provides them, at the highest gold content that can still do the job.

What 750 Means for Your Gold Loan

At the loan desk, the stamp becomes arithmetic. Under the RBI's 2025 directions, pledged jewellery is assayed in the borrower's presence, only the net metal counts, stones and attachments excluded, and valuation runs on the published 22-carat benchmark with lower purities converted proportionately. So 18 carat gold values at its 75% purity against that benchmark: less per gram than a 22 carat bangle, but real, provable value, and the hallmark speeds the assay because the machine reading and the registered purity agree. The loan then sits within LTV caps of 85% up to INR 2.5 lakh, 80% up to INR 5 lakh and 75% above. One caveat borrowers should know: purity floors are lender policy, and many set them around 18 carat, so 750 jewellery generally clears the bar that lower purities may not.

How IIFL Finance Can Help

For turning hallmarked 750 jewellery into funds, IIFL Finance runs the full RBI-scripted process on its Gold Loan. The piece is assayed while you watch, the certificate records purity, gross and net weight, deductions and value, and the diamond's weight is excluded before valuation since the loan is against metal alone. Sanction follows the assayed value within the tiered LTV caps, disbursal is often same-day, and no income proof is required up to INR 2.5 lakh. The jewellery, stones and all, is stored securely and returned within seven working days of full repayment under RBI rules. Carrying the invoice and the HUID details shortens the verification conversation noticeably, subject to eligibility and scheme terms.

Conclusion

The 750 stamp is three digits doing heavy lifting. It certifies 75% purity with legal backing, it explains why the diamond above it stays put, and it converts into provable rupees at every resale, exchange and pledge the piece will ever meet. So treat the 18 carat hallmark as part of what you are buying: check the triangle, the 18K750 grade and the HUID before paying, verify the code on the BIS CARE app, and file the invoice with the purity recorded. The diamond draws the eye. The little number inside the band is what protects the money.

Disclaimer : The information in this blog is for general purposes only and may change without notice. It does not constitute legal, tax, or financial advice. Readers should seek professional guidance and make decisions at their own discretion. IIFL Finance is not liable for any reliance on this content. Read more