Opal is a gem formed from silica-rich waters. It takes its name from the Sanskrit word Upala which means precious stone. Later, it would be called Opallios during Roman times. There are two kinds of Opal – the common opal and the precious opal. The gemstone has been associated with the sacral chakra, imbalances of which can cause problems with addictions. Some people believe that opal can help moderate and harmonize sexual desires. European cultures have long believed opal is a symbol of hope, purity and truth. This Bullet shaped Opal Pendant measures 4cm x 1cm and is suspended from an 18 Inch Silver plated Chain. October Birthstone. Those born in October enjoy two spectacular birthstones to commemorate their birthdays – opal and tourmaline. Both October birthstones have endless colour combinations and beautiful colouring characteristics.