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. 1894 edition. Excerpt: ...one head by Hauy, although relationship of species in crystallization had been observed by the early crystallographer, Rome" de Lisle. The oxide of aluminum in its purest state is perfectly colorless and transparent; but it is seldom found in this condition; corundum is generally tainted by some oxide of metal. The purer kinds of fine colors, transparent and translucent and useful as gems, are known as sapphires; the dull colors, not transparent, are called corundum; while the black or grayish-black variety intimately mixed with oxide of iron, either magnetite or hematite, is distinguished as emery. SAPPHIRE. The variety termed "Sapphire" includes all those kinds of corundum, which, on account of their purity in color, transparency and translucency, may be used as gems. Under this head, therefore, are grouped many stones having individual names. For simplicity in classification, jewelers have adopted the following table. It will be observed in this table that shades of red are classified as "Rubies," while any other color, or those destitute of color, pass under the head of "Sapphire" --Jeweler's Classification Of Sapphire. red. Ruby. True Ruby or Oriental Ruby. Anthrax (Theophrastus) Carbunculus Lychnis (Pliny) Ruby shades of red. Oriental Amethyst purple. Sapphire. True Sapphire blue. Sapphire shades of blue. Sapphire, (Diamond Spar) )... (Adamas, Pliny) Oriental Topaz yellow. Oriental Emerald green. Star Sapphire... Asteria (Pliny). Ruby.--This is pre-eminently the most important of the "precious stones " of this species. Its marvelous beauty, which induced worship from the ancients, has ever awakened an allied feeling in the hearts of Christians. Stones of true "pigeon's blood..".