6
PRINCIPAL GEM SPECIES
An excursion into the literature of gems would reveal that there is much to be discovered about them other than the cold facts of gemology, techniques of gem cutting, and tales of gem lore. When all the information about an individual species is assembled, it provides a sketch of a fascinating gemstone personality. Whole books have been written about diamond—books filled with essays on its mining history, natural occurrences, scientific significance, and best known cut stones.
In the following sections of this book, some of the facts about several of the better known gem species have been gathered. The treatment is not meant to be complete, but enough information is given so that the Museum visitor may better understand and remember what he has seen.
For each species described there are color illustrations of certain gemstones displayed in the collection. Several photographic and artistic techniques have been used to emphasize the various aspects of the beauty of these stones, many of which are the largest and finest of their kinds known; however, not all of the finest gems are pictured here.
At the end of this descriptive section is a list of the significant faceted gemstones in the collection. Obviously, this list will change, because new gemstones constantly are being acquired.
DIAMOND
Diamond is the king of gems. It is a form of pure carbon, and it is the hardest substance known; only diamond will cut diamond. It is interesting that the humble graphite, its close relative, is also pure carbon, but graphite is so soft that it is used as a lubricant and for making the “lead” in pencils.
The ancients believed diamond to be indestructible, and even today many people believe that diamond cannot be broken. Despite its great hardness, however, diamond is not exceptionally tough, and it can be split along what diamond cutters call its grain.
The diamond’s high brilliance results from its very high refraction, or ability to bend light, and its fire is caused by its high dispersion, or ability to divide light into its rainbow colors. However, only in properly cut stones are diamond’s brilliance and fire developed to their maximum.