Lot 3169. Rich Black Opal-"The Black Prince II", Lightning Ridge, New South Wales, Australia. Weighing approximately 36.92 carats and measuring 31.5 x 20.2 x 8.4mm. Estimate US$ 65,000 - 85,000 (€ 55,000 - 72,000). © Bonhams 2001-2018

A "nobby" opal, known in the opal trade as "black liquid", this particular example displays a midnight black body color and predominantly vivid, electric green play-of-color with flashes of turquoise, orange and crimson. Having true black potch to the reverse side, the face exhibits what may be termed a "cathedral window" pattern of play-of-color. 

Bonhams. THE WORLD OF GOLD, OPALS AND OTHER "PHENOMENAL" GEMS, 15 May 2018, 10:00 PDT, LOS ANGELES