Emerald is a deep green beryl with a Moh's hardness of 7.5 - 8 and is both the 20th and the 35th wedding stone.
Emeralds are frequently oiled to fill fractures and are rarely eye clean. They are brittle and sensitive to heat. To clean emeralds, use a damp cloth or spray with window cleaner and wipe them dry.
Historically stones came from Cleopatra's mines in Egypt but today the best stones come from Columbia.
Many emeralds found in jewelry stores today are created in a laboratory and are not natural stones. Emerald is reported to have healing properties with headaches and sciatica.