Gemstone exhibition & trading/gem testing laboratory/ gemology class - introduction to gem & gemology: a basic introduction to major gemstones commonly found in the Cambodian marketplace. This beginning-level course stresses the important aspects of such gems as ruby, sapphire, zircon, peridot, garnet, topaz, aquamarine, crystalline quartz, chalcedony, obsidian. How not to fall into the trap of fake gemstones sellers? How to recognize natural gemstones, synthetics, treatment?