A thousand parts
Silver fineness is commonly expressed in parts per thousand by mass. Sterling silver has a fineness of 925: 92.5 per cent silver, with the balance consisting of other metals. A fineness of 999 means 99.9 per cent silver. These are composition standards, not descriptions of an object's size, price or craftsmanship. Two equally heavy objects can therefore contain different amounts of silver even when their surfaces look similar. The numbers describe the metal, not the value of the finished object.
Separate weight from content
Consider two hypothetical objects, each containing 100 grams of metal. At exactly 925 fineness, one contains 92.5 grams of silver. At exactly 999 fineness, the other contains 99.9 grams. The difference is 7.4 grams of silver. The calculation is metal weight multiplied by fineness divided by 1,000. Use the relevant metal weight: a decorative object may also contain stones, handles or other components that should not be counted as silver alloy. Actual composition depends on the product, its assay and the applicable standard.
Read the whole mark
A bare number such as 925 is a claim about fineness; it does not by itself prove authenticity. In the UK hallmarking system, the compulsory hallmark combines a sponsor's mark, a fineness mark and an assay-office mark. Together these identify the responsible sponsor, the precious-metal standard and the office that tested and marked the article. The fineness mark indicates a minimum standard under that system. Marking practices and legal requirements differ between countries, so the UK example should not be treated as a universal rule.
A useful comparison
When comparing silver objects, separate three questions: how much metal is present, how much of it is silver, and what else the price includes. Design, fabrication, provenance and selling costs can all affect the asking price. A higher fineness alone does not establish that an object is better suited to a particular use. Reliable specifications, appropriate testing and traceable documentation provide context that colour or an isolated stamp cannot supply.
Sources & further reading
- UK Government · Hallmarking guidance notes, November 2022 ↗
- Birmingham Assay Office · Understanding hallmarks and your jewellery ↗
Sources checked 14 November 2026. Reference organisations do not endorse this website. Price examples are hypothetical and educational.