PURITY CONVERTER + LIVE VALUE
Translate Karat, fineness and gold percentage without rounding away the meaning
Enter the purity format you know and the other two update immediately. Add weight to separate calculated pure-gold mass from alloy mass and use the live, source-labelled market reference to estimate metal value. The stamp decoder translates common numeric and Karat marks but never treats a mark as proof of authenticity.
Price reference
Shows the source and observation time of the metal price used here. Product premiums, dealer quotes and taxes are separate.
- Source
- No provider
- Observed
- Observation time unavailable
- Age
- Checking age…
- Delivery
- No data layer available
Checking the current market reference.
Karat ÷ 24 = purity · purity × 1,000 = fineness · purity × 100 = gold content percentage.
Decode a numeric or Karat stamp
A stamp is not proof of metal identity or purity. This tool only translates the characters entered.
Karat, fineness and percentage use the same underlying ratio
Karat expresses gold content in 24 parts. Millesimal fineness expresses it in 1,000 parts, while percentage expresses it in 100 parts. An 18K alloy is therefore 18 ÷ 24 = 0.75, equal to 750 fineness and 75% gold by mass. A stamped value may be rounded to a recognised specification, so a conversion and a stamped designation are not always numerically identical.
Karat to percentageKarat ÷ 24 × 100. Example: 14 ÷ 24 × 100 = 58.3333%.
Karat to finenessKarat ÷ 24 × 1,000. Example: 22K = 916.6667 mathematical fineness.
Pure-gold weightTotal weight × purity fraction. Ten grams at 75% contains 7.5 calculated grams of gold.
Metal valuePure-gold grams × source-labelled 24K reference price per gram.
Common gold purity reference chart
These rows are conversion references. Product standards, permitted tolerances and hallmark rules vary by market and require jurisdiction-specific verification.
| Karat | Gold content | Common fineness | Context |
|---|---|---|---|
| 24K | 100% mathematical basis | 1000 | 999 or 999.9 are common fine-gold specifications |
| 23K | 95.83% | 958 | High-purity alloy |
| 22K | 91.67% | 916 | Jewellery and some bullion coins |
| 21K | 87.50% | 875 | Jewellery alloy |
| 20K | 83.33% | 833 | Jewellery alloy |
| 18K | 75.00% | 750 | Fine jewellery |
| 16K | 66.67% | 667 | Less common jewellery alloy |
| 14K | 58.33% | 583 or 585 | Common jewellery alloy |
| 12K | 50.00% | 500 | Half gold by mass |
| 10K | 41.67% | 417 | Lower-karat jewellery |
| 9K | 37.50% | 375 | Jewellery alloy |
| 8K | 33.33% | 333 | Jewellery alloy in some markets |
What a hallmark can and cannot tell you
A numeric mark such as 750 can be translated as a claimed 750 parts of gold per 1,000, equivalent to 75% or 18K. A Karat mark such as 14KT can be converted in the same way. Marks including GP, GEP, HGE, RGP or GF commonly describe a surface layer or filled construction rather than a solid-gold fineness, so total item weight cannot be multiplied by the surface Karat to obtain gold content.
Why testing still matters
A mark may be worn, incomplete, unrelated to purity or applied incorrectly. Colour and magnet response are also not conclusive. For a material transaction, use an appropriate assay or qualified professional test and keep the test method with the valuation record.
Frequently asked questions
What does 585 gold mean?
As a fineness value, 585 means 585 parts gold per 1,000, or 58.5% by mass. Its mathematical Karat equivalent is 14.04K; it is commonly associated with a 14K product specification.
What does 750 gold mean?
750 fineness equals 75% gold by mass and converts exactly to 18K.
Why does 22K convert to 916.67 instead of 916?
The mathematical conversion is 22 ÷ 24 × 1,000 = 916.6667. A product mark may use a rounded or specified fineness such as 916.
Is 24K exactly 100% pure?
Twenty-four Karat is the mathematical pure-gold basis. Physical products normally state a measurable fineness such as 999 or 999.9 rather than claiming absolute purity.
Does a 750 stamp prove an item is gold?
No. The calculator translates the claimed numerical value only. Verification requires examination and an appropriate test.