Gemstones and their distinctive Characters

Excerpt: "It has been my endeavour to provide in this book a concise, yet sufficiently complete, account of the physical characters of the mineral species which find service in jewellery, and of the methods available for determining their principal physical constants to enable a reader, even if previously unacquainted with the subject, to have at hand all the information requisite for the sure identification of any cut stone which may be met with. For several reasons I have dealt somewhat m...