Fineness
Also: Purity, Fine gold content, Carat
Fineness states how much pure precious metal an alloy contains — expressed in thousandths (e.g. 999) or in carats (e.g. 585 = 14 carat).
Fineness — sometimes called purity — describes the proportion of pure precious metal within an alloy. Pure precious metals are too soft for many purposes, so they are mixed with other metals (copper, silver or palladium, for example). Fineness tells you how large the share of the actual precious metal is in that mixture.
Two notations: thousandths and carats
There are two common ways of writing fineness:
- Per mille / thousandths: 999 means 999 parts in 1,000 are fine gold — that is, 99.9%. This figure now appears on almost all bars and bullion coins.
- Carat (for gold): here 24 carat = 100% fine gold. 18 carat corresponds to 18/24 = 750/1,000.
The most important gold alloys at a glance:
| Carat | Fineness | Fine gold share |
|---|---|---|
| 24 kt | 999 | 99.9% |
| 22 kt | 916 | 91.6% |
| 18 kt | 750 | 75.0% |
| 14 kt | 585 | 58.5% |
| 9 kt | 375 | 37.5% |
| 8 kt | 333 | 33.3% |
Why fineness governs value
The material worth of a piece of jewellery depends directly on its fineness. A 585 gold ring holds only 58.5% fine gold — the remainder is copper and silver, which add almost nothing to the precious-metal value. To work out the pure metal value (the melt value), you multiply the weight by the fineness and the current gold price. That is exactly what the melt value calculator does automatically — including mixed lots of 333, 585 and 750 gold.
The fineness hallmark
In Ireland, precious-metal articles carry a hallmark struck at the Assay Office of Dublin, one of the oldest continuously operating assay offices in the world. Irish hallmarking is compulsory for articles sold as gold, silver, platinum or palladium above the exemption weights, and the mark guarantees the stated fineness — for example "750" for 18-carat gold or "925" for sterling silver. Dental gold usually carries no mark at all; here the specialist dental gold calculator helps, assuming the typical alloys between 750 and 900.
In brief
Fineness is the key to material value: without it you cannot derive a dependable figure from weight and the daily price. Anyone valuing jewellery or scrap gold should always determine the fineness first — from the hallmark or through an expert test.