These images are for a piece of rough opal sold on eBay. The first is with normal light, showing the color play. The second is with light from below, showing that look. The reason for the second image on eBay was to show "no cracks" in the stone, something important to gem buyers. These gems may be put "underwater" and then using manual focus get a really good look. The water makes the uncut stone appear polished and the colors jump out. Just be sure there are no "cat hairs" floating in the water!