If a gem’s surface appearance looks metallic or as if it is painted with glitter, it is said to display aventurescence.
This optical effect happens within certain gems which feature a large amount of small disk or plate like inclusions of a mineral with a highly reflective surface (usually haematite, Pyrite or goethite). These inclusions act like tiny mirrors and produce one of nature’s most fascinating optical effects.
In the mid-18th century, an Italian glass blower was said to have accidentally knocked a jar of copper filings into the molten glass he was using to create vases, and to his surprise the result was a beautiful glass featuring a metallic sparkle. The technique became widely adopted across Europe where it was used to make both jewellery and ornaments. The glass became known as “ventura”, which was derived from the Italian word meaning “by chance”. During the following century, a Green Quartz was discovered in Brazil which naturally produced a similar appearance to the Italian glass and was therefore named Aventurine. This is one of the few occasions in gemmology where a gemstone has been named after a manmade item. In addition to Aventurine, only a handful of other gems have been discovered that demonstrate this stunning lively effect, such as Moonstone, Sunstone and Labradorite.
