Spinel has a long history of being mistaken for ruby due to its similar appearance. The two gemstones are often found in the same environments and are both red in color, making it difficult to distinguish between them.
The confusion between spinel and ruby dates back to ancient times, when the two gemstones were often used interchangeably. In fact, many famous rubies in history were later discovered to be spinels, including the Black Prince's Ruby, a large red gemstone that is set in the Imperial State Crown of England, and the Timur Ruby, a large red gemstone that is part of the Crown Jewels of the United Kingdom.
The confusion between spinel and ruby persisted for many centuries, and it was not until the development of modern gemological techniques in the 20th century that the two gemstones could be reliably distinguished. Today, spinel is still often referred to as the "ruby imposter," although it is now more widely recognized as a distinct gemstone in its own right.
Despite its long history of being mistaken for ruby, spinel is now valued in its own right for its beautiful and varied colors, which range from red to pink, orange, yellow, green, blue, black, and colorless. It is a relatively hard gemstone, ranking between 7 and 8 on the Mohs scale of mineral hardness, and it is often used in jewelry and other decorative objects.