Traité des diamants et des perles, où l'on considère leur importance, on établit des règles certaines pour en connoître la juste valeur, et l'on donne la vraie méthode de les tailler. On y trouve aussi des observations curieuses, également utiles aux négociants, et aux voyageurs, & qui intéressent même la politique

8vo (195x122 mm). [8], XXXV, [1], 104 pp. and 10 engraved plates. Head-piece on top of the dedication engraved by C.N. Cochin fils after Baquoy. Woodcut initials, head- and tail-pieces. Contemporary mottled calf gilt, marbled endleaves, red edges (spine restored, slightly worn and rubbed). Slightly uniformly browned. A good copy.

First edition in French, dedicated to the Prince of Condé, of the successful Treatise on Diamonds and Pearls by the English jeweller David Jeffries in the translation made by Chappotin S. Laurent of the Bibliothèque Royale on the second English edition, enlarged and corrected (London, 1751). Compared to the first edition of the previous year, the second edition added sections on Brazilian diamonds, alternative methods of valuation and the Indian cut.

“The first book in English to describe how diamonds and pearls can be evaluated on the basis of the factors of size (or weight) and style of cut, with allowances being made in the case of diamonds where cut stones depart from the ‘ideal' proportions that were accepted as standard in Jeffries' time. These proportions are radically different from those now considered acceptable because they were based less on the production of maximum brilliance than on retention of the greatest amount of weight from the cutting of a typical octahedral diamond crystal. The ‘ideal' cut in Jeffries' time is a cushion brilliant, ‘old mine' cut, with the pavilion much deeper than employed in modern stones. The proportions and facet patterns are shown in the figures on Plate 1 and others following. Also shown are rose cut gems, graduated as before according to size and weight. The text explains the cutting procedure, how the evaluation rules were derived, the importance of imperfections and flaws as affecting price, notes on rough diamonds, previous authors who attempted to establish valuation rules, and finally, a somewhat similar procedure for the valuation of pearls, with highest values accorded to pearls of closest approach to spherical perfection, luster, etc.... Being understandable in its explanations and providing accurate tables, this work immediately won acclaim” (J. Sinkanskas, Gemology, an annotated bibliography, London, 1993, no. 3195 for the first edition).

“An example of a book that is of both artifactual and intellectual value to jewelry historians is David Jeffries' A Treatise on Diamonds and Pearls written and published in 1750, which describes the commercial aspects of cut diamonds, establishing guidelines for evaluating, pricing, and defining diamond cutting styles. This book is thought to be one of the first books to discuss these topics, and it is listed as a source by many of the authors of the early books found in the core bibliography” (Ch. De Bow Klein, Jewelry History: A Core Bibliography in Support of Preservation, Washington, 1992, available online).

Brunet, III, 526; Sinkanskas, op. cit., no. 3198; Catalogo unico, IT\ICCU\RMRE\000847.

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