• montana sapphires and yogo sapphires - treated and untreated

    Sapphire

    Can you guess which of these stones have undergone heat treatment? The pink and yellow stones have natural colors, and the green and blue stones have undergone heat treatment to enhance clarity and intensify color. © Earth's Treasury. Used with permission.

    Article: Why We Love Montana Sapphires and Yogo Sapphires

    Credit: Earth’s Treasury

    GemstoneSapphire, Corundum
    Natural or man madeNatural
    OriginUnited States
    Origin detailsYogo, Montana
    Gem StateFaceted
    ColorYellow, Green, Blue, Pink
    TransparencyTransparent