More sapphires are found in Montana than anywhere else in North America. Sapphires were first discovered during the mid 1800's, around the time gold was discovered, in Montana. There are several locations throughout Montana were sapphires are found. The most productive site being Rock Creek near Phillipsburg, Montana. The term "Montana sapphire" refers to sapphires found at all locations at Montana, other than Yogo Gulch.
Montana sapphires are routinely heat-treated to enhance their appearance due to their natural poor coloring and quality. The practice of heat-treating stones to improve their color and appearance dates back to the beginning of time. Heating stones is a permanent treatment under normal wear. Modern techniques have produced more controlled and predictable outcomes than earlier primitive methods. Due to advancements in heat-treating and new sophisticated equipment, like computer-controlled furnaces, the outcome is a beautiful affordable gem. Treated stones can cost considerably less than an equivalent stone in shape, size, and color that has not been treated in any way.
One of the greatest attributes of Montana sapphires is their variety of color. The term "sapphire" refers specifically to the color blue. When the mineral species that produces sapphire is the right saturation and hue of red it is considered a ruby. It is very rare for a Montana sapphire to have the deep red color to be considered a ruby. Sapphires of every other color, except blue and red, are considered "fancy" colored sapphires.