Following is a transcript of the video. 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.

many of the fossils that miners find will be destroyed in the search for valuable opal. "There was supposedly a crocodile on the eastern fall that had been found and all red on black ...

The most valuable black opal features bright red stone against a very black base. In the '80s and '90s, gem-quality brown diamonds were worth about $1,500 per carat, but now many sell for up to $ ...