In this video, I take 1400 carats of fine Coober Pedy opal with distinct black opal and white opal layers and make some amazing cabochons with it. The material is very unusual, in that the black opal very much resembles that seen from Lightning Ridge. Opal is a gemstone made of silica whose molecues are arranged in small groups with a round shape. The alignment of the silica "balls" is what determines if the opal wil have color (gem opal - gemstone) or have no color (common opal or "potch").