Spinel is a good candidate for the title of “History’s Most Underappreciated It has long been mistaken for ruby by emperors and monarchs. Many of the famous “rubies” of history were actually spinels. The famous 14th century Black Prince’s Ruby in the British Imperial Crown is actually a red spinel.
People have probably used tourmaline as a gem for centuries, but until the development of modern mineralogy, they identified it as some other stone (ruby, sapphire, emerald, and so forth) based on its coloring.
Tourmaline comes in a variety of different colors. In fact, it has one of the widest color range of any gems species.
Birthstone for October and the gem for 8th anniversaries.