How to Check Gold Purity

Purity is the single biggest variable in what you pay per gram. These are the checks worth doing, in order of reliability.

1. Read the hallmark

Every hallmarked item in India carries three marks: the BIS logo, the purity grade (916, 750, 585), and a six-digit alphanumeric HUID. The marks are small — ask for a loupe, every jeweller has one.

2. Verify the HUID

The HUID is unique to that individual piece. It can be checked in the BIS Care app, which returns the jeweller, the item description and the certified purity. If the app returns nothing, or returns a different item, do not complete the purchase.

3. Ask for an assay test

BIS-recognised Assaying and Hallmarking Centres will test an item for a small fee — the standard method is X-ray fluorescence (XRF), which is non-destructive and takes minutes. For older, un-hallmarked family gold, this is the honest way to find out what you actually own before selling.

4. Counter-side sanity checks

These do not replace an assay, but they catch obvious problems:

• Magnet test. Gold is not magnetic. If the piece is pulled by a strong magnet, there is a ferrous core.
• Density. Gold is very dense (19.3 g/cm³). An item that feels light for its size deserves a second look.
• Discolouration. Look for wear at edges and clasps where plating rubs through first.

When you are selling old gold

The buyer will test it themselves, usually by XRF or by touchstone. Ask to watch the test and to see the reading. Also ask, up front, whether they are quoting on gross weight or net weight after deducting stones, enamel and solder — that deduction, not the rate, is where most disputes start.