As the State gemstone, the Montana Yogo sapphire is a distinctive and natural treasure.  These unique and valuable stones were formed deep in the ground, millions of years ago and discovered in the Little Belt Mountains of central Montana in the late 1800’s.  Prized for its unmatched beauty and highly sought after, it seems only fitting that we name our first ladies only model after this masterpiece of nature found only in the Treasure State. View Watches.