Lower-quality stones, which are naturally greyish, are often heat-treated to darken and turn them into black diamonds. Gems made this way are significantly less expensive than naturally black ...

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 ...

High-quality black opal can cost over $10,000 per carat, making it one of the world's most expensive gemstones. Over 90% of black opals come from Australia, but they aren't easy to find.

Gemstones have been a topic of fascination to human beings for centuries, not just for their beauty, but also for how rare they are, what they symbolise, and that they are worth millions.

But this is true. The world’s most expensive stone is not diamond but the rarest mineral is kyavathuite and painite. According to information, minerals are found almost everywhere on earth.