Montana Sapphire Round Stud Earrings Sterling Silver 4mm stones .60 ct total. These are Rock Creek Montana Sapphires from the Gem Mountain, Philipsburg area of Montana. Keep in mind these are natural stones and color will vary from blue to blue/green and shades of lighter to darker. We do show photos of different colors and shades. All of our Montana sapphires come with a certificate of authenticity and come in a quality gift box.