This is a collection of casts from gems by James and WilliamTassie in the late 18th century England. This collection consists of 15,800 impressions in coloured pastes, white enamel and sulphur from gems in the principal collections of Europe. This collection is in four stained wood cabinets with illustrated letter-press.

The practice of making casts of engraved gems, and thus of circulating their images, was common from ancient times, and became widespread among Roman connoisseurs in the eighteenth century. In London from the 1760s onwards, the Scotsman James Tassie (1735–1799), and later his nephew William Tassie, sold casts of engraved gems made from a hard vitreous paste which James has helped to develop and which could be coloured to resemble gemstones, as well as 'enamel' or white glass, and the cheaper sulphur and plaster. Demand was huge, and Tassie built up a collection of moulds taken from hundreds of cabinets all over Europe, from which he made his casts. Eventually the Tassie catalogue encompassed 20,000 items. The sale of casts of gems boomed as they became an essential souvenir of the Grand Tour, and firms set up in business to sell boxes of trays with identifying lists, or casts in boxes disguised as books for the library shelf, but none would rival the comprehensive scope of Tassie.