Karat & Purity
What 22K, 916 and 999 mean, how to convert between them, and why the purity on the bill matters as much as the weight.
Two ways of writing the same thing
Karat (K) counts parts of pure gold out of 24. 24K is (almost) pure gold. 22K is 22 parts gold and 2 parts other metals such as copper or silver, which make it hard enough to wear.
Fineness counts parts per thousand. 22 ÷ 24 = 0.9166…, so 22K is written 916, meaning 91.6% gold. This is the "916 gold" your jeweller talks about.
| Grade (as stamped) | Gold content | Typically used for |
|---|---|---|
| 24K999 | 99.9% | Coins and bars. Too soft for most jewellery. |
| 24K995 | 99.5% | Bars and biscuits. |
| 23K958 | 95.8% | Some traditional jewellery. |
| 22K916 | 91.6% | Most gold jewellery in India and the Gulf: chains, bangles, necklaces. |
| 20K833 | 83.3% | Some regional jewellery. |
| 18K750 | 75.0% | Diamond and stone-set jewellery; holds settings firmly. |
| 14K585 | 58.5% | Lightweight and everyday diamond jewellery. |
Convert any value with the purity converter.
Pure gold content
To find how much pure gold a piece contains, multiply its net weight by its fineness:
Example: a 22K916 chain with a net weight of 20 g contains 20 × 0.916 = 18.32 g of pure gold.
This is also why the rate of the day on a bill is quoted for a particular purity. The 22K rate is roughly 91.6% of the 24K rate. When you compare two bills, compare the purity as well as the weight.
Silver
Silver uses the same fineness system. 925 ("sterling") is 92.5% silver and is common for jewellery. 999 is used for coins and bars. Traditional Indian silverware such as lamps, plates and anklets varies widely, often 800 to 925. Unless it's hallmarked, the only way to know is to have it tested.
How purity is tested
- XRF ("karat meter"): a quick X-ray scan of the surface that doesn't damage the piece. Many jewellers have one. It's good for a first check but can be misled by plating.
- Fire assay: a small sample is melted and weighed. It's the most accurate method, and it's what hallmarking centres use.
- Touchstone: the traditional streak test. It's quick, but depends on the tester's skill.
What about "KDM"?
"916 KDM" was an old way of selling 22K jewellery joined with cadmium solder. Cadmium is toxic to goldsmiths and is no longer used. Today the term means nothing about purity: only the BIS hallmark grade does. If a bill says KDM but shows no hallmark or HUID, treat the purity as unverified.
What to record in Tijori
Enter purity exactly as marked, e.g. 22K, 916, 999 or 925. Enter gross weight, and net weight if the piece has stones. With both, anyone reading your register later can work out the gold content.