Green onyx is an alternate birthstone for the month of May, the traditional stone being emerald.
Green onyx is a type of chalcedony, a mineral made up of silicon dioxide. It is typically green in color due to the presence of iron and other minerals. Emerald is a variety of the mineral beryl and its green color comes from trace amounts of chromium and vanadium.
Historically, green onyx was used by both ancient Greek and Roman soldiers to protect them during battle. Emerald gemstones were mined in Egypt as early as 330 BC, and Cleopatra is said to have been particularly fond of the beautiful emerald.
Green onyx is a symbol of tranquility and cleanliness, and some claim that wearing this relaxing green gemstone relieves you of anxiety and distress. The emerald has been known as a symbol of truth, love, and loyalty. Some believe the emerald is a stone of inspiration and eternal patience.