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.

When the holy water accidentally splashes her opal hair clasp, the stone fades to black, leaving it as “colourless as a common pebble.” Lady Hermione collapses in pain and is reduced to ...