October Birthstone(s): Opal and Tourmaline October 28 2014

Those born in October are lucky enough to have two beautiful gems to represent their birth month: opal and tourmaline.

Opals are formed in near-surface volcanic rocks from hydrated silica material that is held together by more silica and water, which makes it extremely soft. The appearance can be easily altered by changes in heat and pressure due to the varying amounts of water within it. Opals are famous for their coloring because most stones flash the colors of the rainbow when moved due to the play of light on cracks and other internal differences. These impurities are what give opals their amazing colors, for example black opals get their color from magnesium oxide and organic carbon in the stone.

The opal always had a positive reputation across all cultures until the Black Death in the mid-14th century, when it was believed to be the cause of death. This was because if someone stricken with the plague wore the opal, it would appear brilliant and colorful until the person died and the stone would lose its luster. In reality this was true, though it was due to the change in the wearer’s temperature that altered the appearance.

Tourmaline is also a stone that exhibits a very broad range of colors, though they are nowhere near as complex as the opal. Some have bi-colored properties, one in particular being the “watermelon” tourmaline from Brazil. With this type, the outer edges of the gem are green that transitions to a transparent zone that give way to pink or red. A very unusual characteristic of the tourmaline is that it attracts small bits of paper, lint, and ash when warmed or rubbed because it becomes charged with static electricity. Benjamin Franklin even used the stone in his studies of electricity. This is the tourmaline’s main claim-to-fame since it is a relatively recently discovered stone.

Pictured below are a cluster of Ethiopian opals that Keith and Wes picked out at a jewelry show in Las Vegas, as well as pink, green, and watermelon tourmalines.