When I was a kitten, I loved collecting rocks and gems. So, I was very excited to talk about your question with my friend Johannes Haemmerli. He studies minerals at Washington State University.
What is a gem? -- How gems form -- Crystals -- Classifying gems -- Physical properties -- Optical properties -- Where gemstones are found -- Mining gemstones ...
Some results have been hidden because they may be inaccessible to you
Show inaccessible results