Explains in non-technical terms how to use the Chelsea filter and synthetic emerald filter to identify diamonds and colored gems, and how to separate natural gems from imitations, treated gemstones...więcej »
Today most people, with some notable exceptions, would agree that humans have been responsible in changing the Earth's atmosphere in dramatic ways over the last two centuries and thus causing 'glob...więcej »
Explains in non-technical terms how to use the refractometer to identify diamonds and colored gems, and how to separate natural gems from imitations, treated gemstones, synthetics, and look-alikes....więcej »