Sapphire jewelry. They also may be created synthetically in laboratories for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires – 9 on the Mohs scale (the third hardest mineral, after diamond at 10 and moissanite at 9.5) – sapphires are also used in some non-ornamental applications, such as infrared optical components, high-durability windows, wristwatch crystals and movement bearings, and very thin electronic wafers, which are used as the insulating substrates of very special-purpose solid-state electronics (especially integrated circuits and GaN-based LEDs). Sapphire is the birthstone for September and the gem of the 45th anniversary.
Logan Sapphire Logan Sapphire The Logan Sapphire is a flawless specimen from Sri Lanka, a cushion-cut stone which possesses a rich deep blue color and is the second largest (blue) sapphire known, weighing 422.99 carats (84.6 g). The cushion-cut stone is one of the world's largest and most famous sapphires (its size about that of an egg) that was cut from a crystal mined in Sri Lanka. The Logan Sapphire is named after Mrs. Polly Logan, who donated the gemstone to the Smithsonian Institution in 1960. The Logan Sapphire is set in a brooch surrounded by 20 round brilliant cut diamonds weighing,