The WorkbenchPricing
Karat, Tunch & Hallmark Decoder
Karat to fineness to trade tunch in one tap — and every BIS hallmark stamp on your jewellery, decoded.
The purity
Say it any way you know it — karat, fineness, purity % or the karigar's tunch — and the other three names appear as you type.
Start from a typical piece
✓Tunch is the trade word for the same purity % — the number your karigar or bullion dealer quotes.
Type into any box and the other three follow — karat is purity × 24 ÷ 100, fineness is purity × 10.
Your shop on the cards
Your shop's name, phone and logo printed on every counter card and reference sheet you hand out.
Checking your Tools Pro membership…
The pieceoptional
Add the piece's weight — the fine-metal line a tunch settlement or old-gold exchange starts from appears below.
Fine metal in the piece
Set a purity above and add the piece's weight — we'll show the fine-metal content your settlement or old-gold exchange starts from.
The common stops
| Karat | Fineness | Purity | Hallmark stamp |
|---|---|---|---|
| 24K | 999 | 99.9% | 999 |
| 23K | 958 | 95.8% | 958 |
| 22K | 916 | 91.6% | 916 |
| 18K | 750 | 75.0% | 750 |
| 14K | 585 | 58.5% | 585 |
| 9K | 375 | 37.5% | 375 |
The stamp on 22K reads 916, not 917 — exact 22⁄24 works out to 91.67%, but BIS certifies 91.6% minimum.
Gold stamps, decoded
916
22K — the everyday Indian jewellery standard; 91.6% gold.
750
18K — 75% gold; the favourite for diamond and studded pieces.
585
14K — 58.5% gold; harder, lighter on the pocket, daily-wear friendly.
375
9K — 37.5% gold; BIS-recognised entry-level jewellery.
999 / 990
Fine gold — coins and bars; too soft to hold stones in jewellery.
Silver stamps, decoded
999
Fine silver — bullion, coins and articles; too soft for most jewellery.
925
Sterling — the worldwide jewellery standard; 92.5% silver.
900
90% silver — the older coin-silver grade.
835
83.5% silver — common in European-style articles.
800
80% silver — heavier articles, utensils and payals.
HUID — the piece's identity
6 characters, letters and numbers, laser-etched beside the purity stamp. Verify any HUID yourself, free:
- Open the BIS Care app on your phone.
- Tap Verify HUID.
- Enter the 6-character code — the registered jeweller, purity and hallmarking centre appear.
BIS hallmarking is mandatory for gold jewellery sales in India; silver hallmarking is voluntary — an unstamped silver piece isn't necessarily impure.
For your counter
Cut-out cards — 916, 750, 585 and 925 in plain words, each with the BIS Care verify step. The template sets the cut: four counter cards, eight pocket cards, or two large stand-up cards. Print, cut along the dashed lines, keep a stack at the counter.
The template
Quick references, one tap
Sellers also ask
What does the 916 hallmark on gold jewellery mean?
916 means 91.6% pure gold — that is 22K, the everyday Indian jewellery standard. 750 is 18K, 585 is 14K, 375 is 9K. The decoder explains every BIS stamp in plain words, plus HUID verification via the BIS Care app.
How do I convert karat to tunch?
Tunch is the trade's word for purity percentage: 22K = 91.6 tunch, 18K = 75 tunch. The converter keeps karat, fineness, purity % and tunch in sync as you type any one of them.
How much fine gold is there in a 20 gram 22K piece?
A 20 g piece at 22K carries 18.32 g of fine gold — weight × purity %, so 20 × 91.6% = 18.32 g. Add the piece's weight in the optional weight step and that fine-metal line appears under the flow. It is the figure a tunch settlement with your karigar, or an old-gold exchange, starts from; making and stones sit on top of it.
What is the HUID number on gold jewellery and how do I check it?
HUID is a 6-character code of letters and numbers, laser-etched beside the purity mark, and it belongs to that one piece. Check any HUID free in the BIS Care app: open it, tap Verify HUID, enter the six characters, and the registered jeweller, the purity and the hallmarking centre appear. Hallmarking is mandatory for gold jewellery sold in India.
Is hallmarking compulsory for silver jewellery in India?
No — silver hallmarking is voluntary in India, while gold jewellery hallmarking is mandatory for sale. An unstamped silver piece is not automatically impure, though a stamped one is easier to sell. 925 is sterling at 92.5% silver, 999 is fine silver, and 900, 835 and 800 are the older, heavier article grades.
My karigar quotes tunch 92 but the piece is hallmarked 916 — which one is right?
Both are purity on the same scale: tunch is the trade's word for purity %, so tunch 92 means 92% gold, while a 916 hallmark means BIS certifies 91.6% minimum. The 0.4 point gap is small but real — on a 20 g piece it is about 0.08 g of fine gold. Type either number in and karat, fineness, purity % and tunch all line up.
Can I print hallmark explainer cards for my shop counter?
Yes — the tool makes an A4 sheet of cut-out cards explaining 916, 750, 585 and 925 in plain words, each with the BIS Care verify step. The Classic, Band and Pocket (eight small cards) templates are free. Tools Pro adds Royal, Heritage, Counter easel, Velvet and Gilt, your shop name, phone and logo on every card, and one-tap gold, silver and tunch reference sheets.