In geological terms gem quality sapphire is rarer than diamond. Sapphire is the term for Aluminum Oxide (corundum). This durable material is the second hardest natural substance and is found in a broad range of colours. Ruby is red or pink corundum, all other colours are called sapphire. Blue is traditional but sapphire can also be clear, green, yellow, gold, purple, peach, colour change or a mix of colours (called parti, rainbow or bi-colored). In Australia, there are three major deposits including New England (NSW), Central Queensland (Anakie, Sapphire, Rubyvale and the Willows over a 900 sq km area) and the Lava Plains in Northern Queensland.
Herkimer Diamond (USA)
These gorgeous gemstones are not actually diamonds, but are double terminated quartz crystals instead discovered within exposed outcrops of dolostone around Herkimer County, New York. The 'Diamond' in their name is due to both their clarity and natural faceting - crystals possess double termination points and 18 total faces (6 on each point and six around the center)