The collection of engraved gems, ancient to neo-classical, formed by George Spencer, fourth Duke of Marlborough (1730–1817), was one of the largest and most important such collections assembled in England during the eighteenth century. Unfortunately, like most of its kind, it fell victim to the financial needs of the collector's descendants. The gems were sold at auction, first in 1875, then finally in 1899, when the collection was dispersed: only a small proportion of the nearly 800 items can now be located.

However, various records were made during the collection's lifetime, including volumes of drawings and more or less extensive catalogues, notably one prepared by a mineralogist, Nevil Story-Maskelyne, in 1870. More importantly, most of the gems were replicated in the form of wax impressions or electrotype casts. These copies now belong to the Beazley Archive, housed in the Classical Art Research Centre (Ioannou School for Classical and Byzantine Studies) of the University of Oxford, and the book under review is essentially a publication of this resource, using colour photographs in support of a new catalogue. Where the gems remain accessible, photographs of the originals complement the illustrations of the nineteenth-century replicas.

This is much more than a straightforward catalogue; its organization breaks decisively away from that of Story-Maskelyne. The Marlborough collection absorbed earlier collections, including that compiled in the seventeenth century by the first great English collector, Thomas Howard, fourteenth Earl of Arundel, who had himself acquired earlier collections, such as that formed by the Gonzaga dukes of Mantua. The new publication reconstructs the full history of the collection, beginning with the pre-Marlborough components and ending with the dispersal and modern vicissitudes of the gems. As a corollary to this approach, the catalogue is arranged in sections based on the constituent parts of the collection: first the Arundel gems, then the eighteenth-century collection of the Earl of Bessborough, then the mass of gems that the Duke of Marlborough gathered from disparate sources.

Within these main divisions, there are subdivisions: for example, the gems which Bessborough acquired around 1750 from the fourth Earl of Chesterfield (who had acquired them in turn from his brother, John Stanhope) and in 1760 from Gabriel Medina, a Jewish merchant from Livorno, are catalogued separately. We thus get a good impression of the ‘family tree’ of a great collection of the Age of Enlightenment, seeing how the different ingredients came together. At the same time, the nitty-gritty of a catalogue raisonné is not neglected. Within the constituent sections the gems are arranged by technique (cameos before intaglios), by themes and subjects, then (in so far as possible) by date. Some of the classifications and identifications can be challenged, but the nature of the material makes this inevitable, and opinions are generally expressed with caution. All in all, neither the student of the history of collections nor the student of style and iconography will be dissatisfied.

After the main catalogue, by John Boardman, an interesting chapter by Diana Scarisbrick plots the various ways in which the gems were set and displayed from the fourteenth to the eighteenth centuries. Here, we encounter one of the few defects of the volume: a certain tendency to be less than systematic. It would have helped to know, before the footnote on p 314, that the mysterious asterisks in the catalogue indicate that an item is discussed in Scarisbrick's chapter; it would also have helped if the drawings in figs 11 to 25 had been given captions – at the moment the reader has almost no information on their date, authorship and location.

But this is a minor quibble. The Marlborough catalogue is an extremely valuable compilation. It is, moreover, a triumph of detective work: much energy has been devoted to tracing the history and present whereabouts of individual gems. At the same time, it is a work in progress: many of the missing pieces may still turn up, and it is clearly one of the purposes of this publication to help in the quest.