Birthstone month: October
Color: Opals come in a variety of colors, but are most often predominantly clear, white, blue, black, or orange (known as Mexican or fire opals)
Moh's Hardness: 5.5-6
Transparency: Translucent to opaque
Opals are best known for the flashes of rainbow-colored light that dance across the surface of the stone. These flashes of light and color refract as a result of the grid-like formation of tiny silica spheres that make up this gemstone. The varying size of spheres changes how light is refracted back to your eye, and thus what color you see in the opal.
Opals are typically cut into a cabochon, or rounded shape, to best show off the flashes of color that opals are so famous for. Because they are a fairly soft gemstone, which can chip or break easily, a soft, rounded cabochon cut is the most safe design for this gemstone.
If you're an October baby, this rainbow colored gemstone is for you!