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.
The Sapphire Necklace songs from the opera were performed at The Crystal Palace, arranged for military band by Charles Godfrey Jr. The overture proved popular and went on to appear in numerous further concerts. Like many of Sullivan's early pieces, the overture is in the style of Mendelssohn and shows that "The Sapphire Necklace" was a more serious work than the comic operas for which Sullivan later became famous. The two other songs, "Over the Roof" and a now-lost recitative and prayer, "Then come not yet," were less successful. Only the former went as far as publication, and neither would appear again at