Chalcedony is a form of quartz. It refers to any translucent, cryptocrystalline quartz with a single color. The colors of chalcedony are bluish, white, or gray. Chalcedony has different species. The most popular are the bloodstone, the blue chalcedony, and the carnelian.
The bloodstone is dark green in color with red spots. It is opaque. The blue chalcedony is mainly from the western United States. These stones are gray blue with a light-to-medium color range. They can also have moderate amounts of pink. The blue chalcedony that is found in Africa is gray to nearly clear blue in color.
Carnelian ranges in color from yellow orange to rich, near reddish orange, to orangey brown, and varies from semi-opaque to highly translucent. Cornelian onyx is a layered stone with a red base and a white upper layer. In all chalcedony, the saturation of color determines the quality and value. The clarity is anywhere between translucent to opaque and is dull in luster.
Spinel is the newest birthstone for August. It is singly refractive like a diamond and has a lot sparkle when faceted. Spinel is a durable natural gemstone which is usually untreated and available in a wide variety of vibrant colors. The most popular color of spinel being red and blue. The red spinel throughout the ages has often been confused with ruby. Red spinel, however, is less expensive than ruby.
In history, the faceted gemstones long believed to be rubies in the British Imperial State crown and the European Crown of Jewels are actually red spinel. Spinel are available in yellow, pink, red, blue, black, purple, and white. The more vivid, vibrant blue are the rarest of the color and tend to be the most expensive.
These stones can be found in Sri Lanka, Myanmar, Thailand, Viet Nam, Russia, Kenya, Cambodia, Madagascar, Pakistan and the U.S.A. It is believed that when worn, the stone enhances creativity, cognitive abilities, and increases protection.