Most notably: Golden Delicious and Opal. These varieties may seem indistinguishable on the surface since they are both yellow ...

Opal apples were also created using gene silencing to prevent browning. Other slow-to-brown types of apples are created by selective breeding and combining different apple varieties that have ...

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.