Opals are some of the most unique gemstones on Earth. They range from milky white to fiery red and deep blue-green, and all have a kaleidoscope of shimmering colors within, called play-of-color. Here ...

Ten years ago, opal dealer Mark Tremonti heard that an exceedingly rare black opal had been unearthed in Lightning Ridge, the remote mining region in the Australian Outback. He quickly flew to the ...