Australian sapphires have come a long way since they were first found along the Cudgegong-Macquarie Rivers in New South Wales in 1851. Once thought to be non-viable commercially, the countrys sapphire mines now rank as the most productive in the world.
No statistics exist on sapphire exports from Australia to the U.S., but you can assume most of the very dark blue ones in stores today originated in Australia. Also available are multicolored sapphires from Lava Fields in northern Queensland, distributed in the U.S. exclusively by William Smith of W&K Jewelry, Mesquite, TX. These sapphires are found in volcanic basalt vents and in alluvial watercourses near the vents. The main deposits of the region are called Wyandotte Hills and Mines Hill.
The multicolored sapphires were first brought to the attention of gem market consultant Stuart Robertson at Gemworld International, Northbrook, IL. They were described to him as particolored, a term usually used to describe variegated colors in tourmaline. The sapphire first appeared to have lively divisions of blue, yellow and green, but closer examination showed distinct blue and yellow zones.
In some of the faceted sapphires, the cutter combines these distinct zones in such a way they appear mostly green face-up. (In diffused illumination, however, distinct blue and yellow are visible.) The samples we observed were relatively inclusion-free, except for minute clouds of needles and small fingerprints.
Australian sapphires generally have iron-rich colors such as dark blue (up to 95% of the total), yellow and green. The volcanic basalt in which they form gives them strong, angular color zoning, according to Ruby & Sapphire by Richard Hughes (RWH Publishing, Boulder, CO, 1997). This feature becomes more apparent in multicolored gemstones.
While emerald-cut sapphires allow the cutter to show 50-50 zones of color, other cuts tend to mix the colors like an artists palette. As a result most of these gems are one-of-a-kind. Meanwhile, pink and red (ruby) corundum is less prevalent in Australia, though some is available in the Harts Range mountains.
- W&K Jewelry, Mesquite, TX; (972) 222-2740.
by Robert Weldon, G.G.