Free tool
Gold Filled Calculator
See roughly how much pure gold is in your gold filled and rolled gold jewellery — and why it’s so much less than the weight on the scales.
Estimated pure gold
2.50 g
in 100.0 g of jewellery — about 2.5%
An estimate from the stated marking — not an offer. Marks are minimums, and wear, repairs, stones, glass, springs and steel pins all change the real figure. Offers also reflect refining costs and the size of your lot.
Hallmark checker
Will We Buy It?
Pick the mark stamped on your piece — on the clasp, inside the ring band or on the watch case back — and we’ll tell you straight away.
Quick test: the magnet
Gold filled and rolled gold are built on a brass or copper core, which isn’t magnetic. If a strong magnet grabs the body of a piece (not the clasp — clasps often contain a steel spring), it’s likely plated steel and usually not worth recovering. It’s a guide only; a non-magnetic piece still needs its mark checked.
How the maths works
Reading a Gold Filled Mark
A mark like 1/20 12K GF tells you two things. The fraction is how much of the item’s metal weight is the gold layer — here 1/20, or 5%. The karat is how pure that layer is — 12K is 12 parts in 24, or 50% gold.
Multiply them together: 5% × 50% = 2.5% pure gold. So a 100 gram pocket-watch chain marked 1/20 12K GF carries roughly 2.5 grams of pure gold — before the costs of separating and refining it.
That’s why gold filled is valued on its recoverable gold content, and why larger lots earn better rates.
| Mark | Gold layer | Pure gold / 100 g |
|---|---|---|
| 1/20 10K GF | 5% at 41.7% gold | 2.08 g |
| 1/20 12K GF | 5% at 50% gold | 2.50 g |
| 1/20 14K GF | 5% at 58.3% gold | 2.92 g |
| 1/10 10K GF | 10% at 41.7% gold | 4.17 g |
| 1/10 12K GF | 10% at 50% gold | 5.00 g |
| 1/10 14K GF | 10% at 58.3% gold | 5.83 g |
| 1/40 10K RGP | 2.5% at 41.7% gold | 1.04 g |
| 1/40 12K RGP | 2.5% at 50% gold | 1.25 g |
| 1/40 14K RGP | 2.5% at 58.3% gold | 1.46 g |
Questions
About the Calculator
The mark says the gold layer is 1/20 (5%) of the metal weight, and that layer is 12 karat — 50% pure gold. So about 2.5% of the item’s metal weight is pure gold: roughly 2.5 grams in every 100 grams.
Gold filled and rolled gold jewellery is mostly brass or copper. Only the thin bonded outer layer contains gold, and that layer is itself an alloy. That’s why gold filled is valued on its recoverable gold content, not its total weight.
No. It’s an estimate based on the stated marking, which is usually a minimum. Wear, repairs, and parts with no gold — stones, glass, springs and steel pins — all change the real figure. An offer is only made after your items are assessed.
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Not Sure What You Have?
Send us a few photos and item details and we’ll help you decide the best next step.