A pair of diamonds that formed hundreds of kilometers deep in Earth’s malleable mantle both contain specks of materials that form in completely opposing chemical environments—a combination so unusual ...

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.

Inside a secure laboratory in New York City geologist Evan Smith is peering into billion-year-old blue diamonds to gauge the inner workings of Planet Earth. The cold, dense objects zap the warmth from ...

What is a gem? -- How gems form -- Crystals -- Classifying gems -- Physical properties -- Optical properties -- Where gemstones are found -- Mining gemstones ...