Properties of a spinel gemstone include that they come in a variety of colors. The gemstones also have a vitreous luster.
Spinel gemstones have a hardness of 7.5 to 8 and a refractive index of 1.712 to 1.736. They come in black, purple, green, yellow and other colors. Natural and synthetic spinel gemstones are available, yet true quality spinels are rare. Deep red spinel gemstones resemble rubies and they are often used in place of rubies in jewelry as a less costly alternative. The gemstones are commonly found in Sri Lanka, Cambodia and Vietnam. Natural spinels are not treated with chemicals or enhanced in any way.