Are you looking for a May birthstone? The stunning green emerald is the birthstone for May. It is a kind of beryl mineral, and vanadium or chromium, in minute proportions, gives it its green hue. Along with the other birthstones, it was made the official birthstone for May in 1912, but before that, it was also connected to the May-born zodiac signs of Taurus and Gemini. Taurus is more common in May, Venus, the planet that rules Taurus, is usually more strongly linked to Taurus.