On an auspicious day in November of 1986,5 Australian miners climbed Lunatic Hill — so named for the mental state anyone would be in to dig there.
While their competitors searched for opals at a depth of 2 to 5 meters, the Lunatic Hill Syndicate bored 20 meters into the earth.
And for their audacity, the earth rewarded them with a fist-sized, record-breaking opal.
They named it the Halley's Comet opal, after the much larger rocky, icy body flying by the earth at that time.
The Halley's Comet opal is a marvel, but its uniqueness is, paradoxically, the most usual thing about it.
While diamonds, rubies, emeralds, and other precious stones are often indistinguishably similar, no two opals look the same, thanks to a characteristic called "play of color."
This shimmering, dazzling, dancing display of light comes about from a confluence of chemistry, geology, and optics that define opals from their earliest moments, deep underground.
It's there that an opal begins its life as something surprisingly abundant: water.
Trickling down through gaps in soil and rock, water flows through sandstone, limestone, and basalt, picking up a microscopic compound called silicon dioxide.
This silica-enriched water enters the voids inside pieces of volcanic rock, prehistoric river beds, wood, and even the bones of ancient creatures.
