A Guide to Montana Sapphires

Perhaps one of the most popular and well known American Gemstones is Montana Sapphire. This is for good reason, too - Montana, known as the “Treasure State,” produces nearly all of the sapphire mined in North America. With the rich blue of Yogo sapphire and fun fancy colors from other Montana mines, it’s easy to find a consciously-mined alternative to sapphires from mines all over the world. Some people love knowing they’re supporting responsible mining, others appreciate the importance of supporting our local economy, and some just love knowing the full story of their gemstones! No matter the reason, we’re here to guide you in choosing a gorgeous Montana Sapphire that’s perfectly suited to you.

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Gem Knowledge

Montana Sapphires are, chemically, the same as a sapphire mined anywhere in the world. They belong to a family of gems known as “corundum.” Rubies are the red type, and all other colors are referred to as sapphire. With a hardness of 9 on the Mohs scale, sapphire is an excellent choice for jewelry that you’d wear every day - it is second in hardness only to diamonds! 

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Mining in Montana

In the mid 1800’s, gold miners discovered small sapphire stones in the pebbles around the Missouri River. At the time, no one thought much of it because gold was the goal. However, as logistics for polishing and gemstone cutting became possible, this local gem drew attention. Today, the deposits surrounding the Missouri River beds produce the largest sized  Montana sapphires! 


Sapphires found amongst the river beds here can range in colors, from pale champagne to green to grey. These sapphires may be heat-treated to bring about more intense, saturated tones. Some of these gems also exhibit a trait known as “color change.” In different kinds of light, a gem might appear to be different colors. For example, it may look more purple in indoor light, and more blue in natural sunlight.


Sapphires from the Yogo Gulch area of Montana have gained a reputation all their own. Unlike other Montana Sapphires, these gems are a vibrant cornflower blue - without the help of heat treatment. These gems are usually on the smaller end, with few above ½ a carat. They are also mined differently. As opposed to being found beneath river beds and alluvial deposits, they are still embedded within their host rock. Miners search for these gems within igneous rocks.

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Perfect For Jewelry

Montana Sapphires are perfect for creating a truly personal piece of jewelry. Because most mines are family-owned and work with miners that are trusted, it’s possible to follow the story of your Sapphire from the mine, to a gemstone cutter, to the jeweler who sets your stone! Plus, the variety of colors that these gems are available in make it easy to find one that fits your style and taste. Whether you fall in love with a ready-made piece from our American Gem Collection, or if you would like us to find the perfect Montana Sapphire for a custom piece of jewelry, you’ll treasure this gemstone for years to come.

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Sami Fine Jewelry