A   Treatise on Diamonds and Precious Stones; Including Their History -- Natural and Commercial; To Which Are Added the Best Methods of Cutting and Po by John Mawe

A Treatise on Diamonds and Precious Stones; Including Their History -- Natural and Commercial; To…

byJohn Mawe

Paperback | May 5, 2014

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1815 edition. Excerpt: ...stones, as the Garnet, and certain semi-transparent ones, as the Chryosprase, are cut en cabochon, with a single or double row of small facets surrounding the base. The form given to the most perfect coloured stones by the French artists, is that of a square or octagon, with a single delicate step between the table and the girdle, and three or four steps between the girdle and the collet. The flatter the ellipse, the more the varying lustre is diffused over the surface of the stone, as, on the other hand, with a high ellipse, it is condensed on a single spot. CHAP. III. RUBY, SPINELLE AND BALAIS EMERALD--CHRYSOBERYL--TOPAZ. X HE colour of the Ruby, when perfect, is a full carmine red, in which state it is known by the name of Spinelle Ruby; when the tinge verges upon rather pale rose red, it is called Balais Ruby; when the red has a decided shade of orange, it usually goes by the name of Vermeil; when of a yellowish red, it is called Ru-bicelle: in other varieties, the red by mixture with blue, becomes crimson, violet, and finally indigo blue, which latter is sometimes so deep, as to be scarcely dis-o tinguished from black; sometimes, though rarely, a greenish blue is observable; these latter varieties scarcely belong to the Jeweller, but are called by the Mineralogist, Ceylanite and Pleonaste. Its primitive and most usual form, is the regular octohe-dron; it also presents the cuneiform octohe-dron, and a few other varieties; sometimes it occurs in rolled grains. In size it very rarely exceeds eight or ten carats; the planes of the crystals are smooth and brightly shining, with a vitreous lustre, and usually exhibit a lamellar structure; the fracture is flat conchoidal, and sometimes imperfectly foliated; the lighter coloured varieties,...

Details & Specs

Title:A Treatise on Diamonds and Precious Stones; Including Their History -- Natural and Commercial; To…Format:PaperbackDimensions:22 pages, 9.69 × 7.44 × 0.05 inPublished:May 5, 2014Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:0217313256

ISBN - 13:9780217313254

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