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Ultra Rare Idaho Star Opal

In the early 70’s the Star pattern in the opal from Spencer, Idaho was discovered. This rare phenomenon was found only in the Idaho opal. When it was found out by the Australians, they were wondering what caused this rarity in the Idaho opal and asked to have some samples of the Idaho star. It was J.V. Sanders, a professor from the University of Melbourne who did the study on the star opal triplet. He determined that this phenomenon occurs only in the opal from Idaho. It was due to the formation of Idaho opal. The Idaho opal was formed by geyser activity in layers, and it was the occurrence of alternating layers of precious and non-precious opal, and with light diffraction, causing the opal to reflect a star.

At the time of the study, there were 2 types of this star phenomenon. 3 ray stars and 6 point stars. A 3 ray star is the shape of a Mercedes emblem. A 6 point star is a 3 ray with a point (or dot of a different color) at the opposite corners. These early stars were from the original Spencer opal mine. When we began noticing the star in our opal, we assigned a number to each one and kept them for our own collection. After we began to build up our inventory of stars, we offered them for sale at a premium price. We also made up a certificate, with the number we assigned to that star, for the buyer. A few years later, we noticed some of the stars we found had the full 6 ray pattern. These are the rarest of the rare star. We now have found about 600 stars of different patterns out of over 100,000 stones we have cut over the 20 years of mining.


The Idaho star opal triplet is most likely the rarest gemstone in the world. Because of this, the Curator of the Smithsonian came to us asking for these for their “star” exhibit in the Natural History Museum in Washington, D.C. We gave them one of each pattern, and they are now on display there.
They range in price of $50-$1,600 each, and are an item for a collector of rare gemstones…and only found in Spencer, Idaho!

We now have these star opals on display for purchase at Montana Gems in Philipsburg – Pictures just can’t capture their true beauty!