Narrator: High-quality black opal can cost over $10,000 per carat, making it one of the world's most expensive gemstones ... % of the world's opal comes from Australia. And a lot of the black ...

The stones once again saw a resurgence in the late 19th and early 20th century when opal deposits were discovered in Australia, and have since waxed and waned in popularity. But this year ...