Obsidian 125 Malachite 126 Jet 128 Amber 128 Coral 130 Table of Hardness and Specific Gravity 132 Index 135 PREFACE. The object of this little book is to convey to the merchant, the workman, and the amateur, in a condensed and accurate form, information concerning the various properties of precious stones. Besides drawing freely on a number of authorities, the author has used his practical experience to indicate such tests as an amateur can readily make. Specific gravity, hardness, and dichroism are tests which are easily mastered, and a thorough understanding of these three properties will assist in classifying doubtful gems. Such stones have been dealt with principally as are used in commerce for jewelry and ornamental purposes. The attention of the writer has often been called to the general lack of knowledge among the jewelers regarding precious stones other than diamonds, rubies, sapphires, and emeralds. As there are so many other beautiful and rare gems which nature yields to man, and which are worthy of the jewelers’ art, the author trusts that his book will awaken a new interest in the fascinating study of mineralogy as applied to precious stones, and that at some future day he may feel encouraged to enlarge upon this treatise. M. D. ROTHSCHILD. 41 and 43 MAIDEN LANE, NEW YORK. HAND-BOOK OF PRECIOUS STONES. WHAT ARE PRECIOUS STONES? The mineral to which the term “precious stone” is applied, must be adaptable for jewelry or ornamental purposes and must possess beauty, hardness, and rarity. The beauty of a precious stone or gem consists of its color or colorlessness, brilliancy or softness of lustre, and transparency. To take a high and lasting polish, a mineral must be hard,—and many stones that would otherwise be highly valued are low in the estimate of worth because they do not possess of sufficient hardness to make them endure the wear and friction to which a precious stone is subjected when used in the form of jewelry. The rareness of precious stones has a decided effect in determining their values. For instance, the crocidolite, commercially known as tiger-eye, was sold by the carat some years ago, and was largely used in the making of fine jewelry. To-day, this material is so plentiful that it is no longer classed among the higher gems, but serves for cameos and intaglios like chalcedony and onyx. The changes of fashion have much to do with determining the market value of precious stones. Amethysts, topazes, cat’s-eyes, aquamarines, alexandrites, and even emeralds and opals have been eagerly sought for at times and then again neglected for other gems, causing a sensible difference in the value of these stones.