Anup Shah / Young Eastern common chimpanzee {Pan troglodytes schweinfurtheii} Opal's baby, Mahale NP, Tanzania.

Anup Shah / Young Eastern common chimpanzee {Pan troglodytes schweinfurtheii} Opal's baby, Mahale NP, Tanzania.

Luiz Claudio Marigo / Opal rumped tanager {Tangara velia} Brazil

Philippe Clement / Tractor sowing seeds with seed drill machine, Cap Gris Nez, Côte d'Opale / Opal Coast, France March

Yva Momatiuk & John Eastcott / Mine tailings from years of mining for opals near Coober Pedy, South Australia, Australia

Yva Momatiuk & John Eastcott / Mine tailings from years of mining for opals near Coober Pedy, South Australia, Australia

Mark Bowler / Campbell's Russian dwarf hamster (Phodopus campbelli) opal colour form

Yva Momatiuk & John Eastcott / Clouds reflected in the Opal Pool, Midway Geyser Basin, Yellowstone National Park, Wyoming

Yva Momatiuk & John Eastcott / Tourists photgraphing Opal Pool, Midway Geyser Basin, Yellowstone National Park, Wyoming

Yva Momatiuk & John Eastcott / Opal Pool, Midway Geyser Basin, Yellowstone National Park, Wyoming

WILLIAM OSBORN / Stewart highway through Outback with spoil mounds from opal mining, Coober Pedy, South Australia

Anup Shah / Eastern common chimpanzee {Pan troglodytes schweinfurtheii} Opal's baby, Mahale NP, Tanzania.

Anup Shah / Portrait of Eastern common chimpanzee {Pan troglodytes schweinfurtheii} Opal's baby, Mahale NP, Tanzania.

Graham Eaton / Opal, hydrated silica, SiO2 nH2O, from Australia