Opals! Photonic crystals ... and packed tightly together in a semi-regular "lattice" FDA approves first new type of pain medication in 25 years 16 Types of Bills You Should Always Pay Before ...

Narrator: High-quality black opal can cost over $10,000 per carat, making it one of the world's most expensive gemstones. But mining black opal isn't easy. After investing tens of thousands of ...