Umoona Opal Mine | Australia | oil mixes

As we gaze out over the harsh Outback, Rowe tells me of all kinds of opal near misses­ - sometimes the difference between going home broke and going home a millionaire is just a matter of inches. Since I wouldn't know opal if it brought me breakfast in bed, Rowe takes me to see Yanni Athanasiadis, a Greek transplant who runs the Umoona Opal Mine and Museum.

ATHANASIADIS IS EXPERIENCED at guessing a few inches to the left or right, and he's been right his fair share of times. I don't know if he was ever broke, but he is no doubt a millionaire now. Piled around his desk are opals of varying qualities and forms. He launches into an explanation best summarized as this: Opal is a mineral derived from silica. It occurs naturally in places­ like Australia because, at one time - like a million years ago or something - the entire country was entirely under water.

Opal is divided into categories of black, black crystal, crystal, dark, light, boulder, and matrix. But it's the kaleidoscope of brilliant colors within the opal - embedded there by a phenomenon similar to the spectrum of colors seen when oil mixes with water or a rainbow crosses the sky - that makes it retirement quality. In general, the darker the background and the more color within it, the more valuable the opal is.

We start at the bottom of the opal chain with a piece of light opal that is a dull, translucent white with faint traces of green and red throughout. Value? About $1,500. From there, we make our way to the good stuff. Athanasiadis pulls out a single black opal barely bigger than a thumbnail that radiates with a breathtaking array of colors and that looks so wholly unnatural, you'd think it was from another planet. This piece alone is worth $250,000, and he has many, many more where that came from.