Convert karat to tunch to percentage to hallmark — then turn it into actual rupees-per-gram melt value with today's gold price. A complete guide for buyers, sellers, and inheritors.
Walk into any Indian jewellery shop and you'll hear three different words for the same thing: karat, tunch (or touch), and fineness. They all measure the same physical quantity — how much of the metal is actual gold versus the copper, silver, or zinc added for hardness. The shop's hallmark stamp adds a fourth notation (916, 750, 585). Most buyers and sellers don't realise these are interchangeable measurements of the same number; you just need one ratio. This guide explains all four notations, then walks through the actual rupee calculation that determines what your gold is worth today.
"Tunch" (sometimes spelled "touch" in English) is the South Asian jewellery-trade term for purity expressed as parts-per-thousand or as a percentage. 22-karat gold is 91.6 tunch. 18-karat gold is 75 tunch. 24-karat (pure) gold is 99.9 tunch. It's the same number a Western refiner would call "fineness" or what the BIS hallmark stamps as "916", "750", or "999".
Jewellers use tunch because it's the form that maps directly to weight calculations — multiply gold weight by tunch (as a decimal) and you get the pure-gold content in grams. "Karat" is older and divides into 24 parts (22K = 22/24 = 91.67%), which is harder to do in your head.
Once you understand that all four are the same ratio, the rest is conversion. The Gold Purity Calculator handles all four simultaneously — type any value and the others update live.
24K = 99.9% = 999 hallmark = 99.9 tunch — pure investment-grade gold (bars, coins).
22K = 91.6% = 916 hallmark = 91.6 tunch — the standard for Indian wedding jewellery and Middle East gold.
21K = 87.5% = 875 hallmark = 87.5 tunch — common in the Gulf.
18K = 75% = 750 hallmark = 75 tunch — common in diamond-set jewellery and Western luxury brands.
14K = 58.5% = 585 hallmark = 58.5 tunch — popular in the US for everyday jewellery.
10K = 41.7% = 417 hallmark = 41.7 tunch — the legal minimum to be called "gold" in the US.
9K = 37.5% = 375 hallmark = 37.5 tunch — UK standard for budget jewellery.
Gold is priced internationally per troy ounce in USD (LBMA, COMEX), and locally per gram in your currency. In India the per-gram 24K rate is published daily by IBJA (India Bullion and Jewellers Association) and is what banks, jewellers, and pawn-brokers reference. Look up "today gold rate per gram" or check IBJA's bulletin for the spot 24K price. Let's use a representative figure for the example: ₹7,200 per gram of 24K.
This is the spot price — what the metal is worth before any of the costs (making, wastage, GST, dealer margin) that go into a jewellery shop's selling price.
For any piece of gold jewellery:
Pure gold weight (g) = Total weight (g) × Purity (as decimal)
Melt value = Pure gold weight × 24K price per gramTwo lines. That's the whole formula.
You inherited a 22K chain weighing 18 grams. Today's 24K rate is ₹7,200/g. What's the pure-gold value?
Pure gold = 18 × 0.916 = 16.49 g
Melt value = 16.49 × 7200 = ₹1,18,728That's the scrap value — what a refiner would pay you for the metal alone, ignoring craftsmanship. The shop you bought it from charged you more (making charges, GST, design premium) and the shop you sell it to will offer you less (their margin) — but ₹1.18 lakh is the honest underlying number.
This one's a trap. Diamond-set jewellery is sold and priced by total weight, but you can't melt the diamonds. The shop should give you a separate gold-only weight on the invoice.
Assume the ring's gold-only weight is 4.2g (the rest is stones and setting). 18K means 75% pure gold.
Pure gold = 4.2 × 0.75 = 3.15 g
Melt value = 3.15 × 7200 = ₹22,680If you sell back, the diamonds rarely fetch their bought-price — lab-grown diamond market and certification issues mean reselling a 0.3-carat solitaire often recovers only 20–40% of what you paid. Treat diamonds in jewellery as a cost, not an investment; the gold is the only part with a liquid resale market.
The price you pay at the shop is:
Buying price = (Gold weight × Purity × 24K rate)
+ Making charges (per gram or % of gold value)
+ Wastage (often hidden in making charges)
+ 3% GST on the total
+ Diamond / stone cost (separately)Typical making charges run 8–25% of the gold value depending on design complexity. Machine-cut chains are at the low end; intricate handcrafted bridal pieces are at the high end. Wastage is often presented as a separate 4–8% line item but is functionally part of making charges — jewellers add it to cover gold lost during shaping.
When selling back, the buyer ignores all of this and pays only the underlying gold value — sometimes minus their own margin of 2–5%. The making charges are a sunk cost; they don't survive resale. This is why gold jewellery is a poor investment vehicle compared to coins or bars: you pay 15–30% in non-recoverable costs on the way in.
If you have 22K gold and need cash:
Outright sale to a jeweller: ~93–96% of melt value, depending on the relationship and metal volume.
Outright sale to a refiner: ~96–98% of melt value, if you can find one and meet KYC.
Gold loan (pawn): ~75% of melt value as principal, repaid with 7–15% APR depending on lender. If you can repay, you keep the gold.
Gold-loan auction (if you default): the lender auctions the gold and recovers principal + interest, returning any surplus — often a worse outcome than outright sale.
If you need cash short-term and intend to repay, a gold loan keeps the asset. If you don't need the jewellery and don't expect to repay, outright sale to a refiner usually nets more cash.
A query we see often: "how to convert 995 gold to 999" or "pure gold to 916 conversion". You can't physically convert one purity to another without remelting, but the value conversion is just the formula:
10 g of 995 gold = 10 × 0.995 = 9.95 g of pure gold
9.95 g pure = (in 916 form) 9.95 ÷ 0.916 = 10.86 g of 916
Useful when a jeweller offers to swap 24K bullion for 22K jewellery (or vice versa) — the gram weights change but the pure-gold mass stays constant. The Gold Purity Calculator does this kind of cross-purity equivalence in one screen.
If a chain has ₹1.2 lakh in gold and the shop charges 15% making, that's ₹18,000 of pure craftsmanship value. Whether it's worth paying depends on your goal:
Wearing jewellery: design and finish matter, making charges are part of the product. Pay them.
Investing in gold: buy coins, bars, or gold ETFs — making charges are pure loss.
Family inheritance: sentimental value justifies the premium; just don't confuse it with a financial investment.
For investment-grade exposure, the Compound Interest Calculator can help you model gold-ETF returns versus alternatives over multi-year horizons.
The 916 hallmark means the piece is 91.6% pure gold — that is, 22-karat gold. It's the BIS standard for Indian wedding-grade jewellery. The remaining 8.4% is alloy metals (typically copper and silver) added for hardness and color.
Purity (as a decimal) = Karat ÷ 24. So 22K = 22/24 = 0.9167 (91.67%, rounded to 91.6 for hallmarking). Use the Gold Purity Calculator for instant conversion between karat, percentage, tunch, and hallmark.
Multiply total weight by purity (as decimal) to get pure-gold grams, then multiply by today's 24K per-gram rate. Example: 18g of 22K at ₹7,200/g = 18 × 0.916 × 7200 = ₹1,18,728 melt value (before making charges and GST).
None — they're the same purity expressed on different scales. 22K = 91.6 tunch = 916 hallmark = 91.6% pure gold. Karat divides into 24; tunch/percentage/hallmark are in parts per thousand or per hundred.
You get the gold's melt value (weight × purity × spot rate) minus the buyer's margin (typically 2–5%). Making charges, wastage, and GST are sunk costs that don't survive resale. Diamonds and stones rarely fetch close to their original price.
Multiply 22K weight by 0.916 to get pure gold grams. That pure gold is your 24K equivalent. Example: 10g of 22K = 9.16g of 24K. The Gold Purity Calculator does this in one click.
Gold purity sounds complicated because the industry uses four different words for the same number. Once you see them as the same ratio — karat, percentage, tunch, hallmark — the rupee calculation is two lines of arithmetic: weight × purity × spot rate. For a quick check of any of these conversions, use the Gold Purity Calculator. For the percentage and making-charge math, the Percentage Calculator is one tab away. When the maths gets stuck, you know the price you're really being charged — and that's the only protection against being overpaid or underpaid on either side of a gold transaction.
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