As the gem of spring, its no wonder why The Emerald is the chosen birthstone for May. It’s also commonly used as the gem for both the 20th and 35th wedding anniversaries. The first known emerald mines were in Egypt, and loved by Cleopatra. It is believed that these mines were worked as early as 3500BC! They are always loved for their vibrant green colour, and carry a Moh’s hardness of 7.5-8.