• ruby and sapphire - gem classification

    Corundum – Natural, Faceted, Red

    Thai ruby (3.66 cts) and Sri Lankan sapphire (2.75 cts). Photo © Joel E. Arem, PhD, FGA. Used with permission.

    Article: A Guide to Gem Classification

    Credit: Joel E. Arem, PhD, FGA

    GemstoneCorundum
    Natural or man madeNatural
    Gem StateFaceted
    ColorRed, Blue
    TransparencyTransparent