Silver Purity: 999 vs 999.9 vs 925

999 silver is 99.9% pure and is the common standard for investment bars and rounds. It is soft, and surfaces mark easily, so bars are often supplied sealed.

999.9 indicates a further refining step to 99.99% purity. It is used where very high purity is required, including certain industrial applications, and generally carries a higher production cost.

925 silver is 92.5% silver alloyed with other metals, usually copper, for hardness. It is the standard for jewellery and tableware rather than bullion trade.

Sterling items are valued on silver content, so gross weight overstates the metal contained.

Silver tarnishes on exposure to sulphur compounds in air. Tarnish is a surface effect and does not reduce silver content, but it affects appearance and therefore resale presentation.