In its Guide Nature Larousse collection, the publisher has just released “Precious stones” : a work allowing to recognize more than 140 gems and cut stones. It is therefore a small mine (the pun was easy!) For all amateurs – informed and professionals – of stones used in particular in jewelry and jewelry. The author, Ronald Louis Bonewitz, has over 40 years of experience as a geologist, researcher, and stonemason.
All about the fascinating world of gems
The guide begins by going over some definitions and some generalities on gems. Let us not forget that they include both precious stones, semi-precious stones, gems of biological origin (amber, pearls) as well as precious metals in their native state.
The geological processes that give rise to mineral gems and the organic processes that give rise to the gems of the same name are explained in detail. A map determines the location of the main gem deposits. The book also explains that the origin of gem names often dates back to Antiquity and that the classification of minerals is based on their chemical formula. What also characterizes gems are of course their physical properties (hardness, density…) but also optical (brightness, refraction…).
Of course, the guide describes the evolution of the exploitation of deposits, over the centuries, as well as the work of stones: cutting, polishing, sculpting, engraving, but also processing certain gems to modify them for example. Today, synthetic gems are even made, at a lower cost than a natural gem, and with a distinction that can be difficult to make.
140 gems in detail
The guide offers a very complete file for each of the 140 gems listed: precious metals (gold, silver, platinum), gems organic (amber, pearls, ivory, mother-of-pearl) and finally precious stones and semi-precious stones with their different varieties (more than 400 in all), classified by chemical family: native elements (diamond), sulphides (pyrite), oxides (beryl, ruby, cat’s eye…), halides (fluorite), carbonates (azurite, malachite…), phosphates (turquoise…), sulfates (alabaster), silicates (amethyst, emerald, opal, garnets…).
For each one, you will know all about its crystalline characteristics (crystalline system, hardness, density, brightness…), its possible cut types, its main uses in jewelry, etc… And magnificent photos will help you identify the gems: close-up on the cut gem, photo of the crystals in their natural state.
Finally, a glossary will make you unbeatable on the language used by gemologists!