When you think of expensive gemstones, what comes to mind? Most people think of the Big Four ... who found it kept it hidden under his bed for 10 years. Coral, especially red coral, is considered ...

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 ...

Known for its deep red hue, rubies are highly prized and valued at around $4,625 per carat. One of the hardest and most sought-after gemstones, diamonds cost approximately $9,502.13 per carat. A light ...