How To Clean Emeralds
Because of the inclusions within an Emerald, it is not wise to clean these gems in an ultrasonic cleaner. Instead, clean gently by hand using warm water.
Most Emeralds are usually treated by filling the Emerald with oil to fill in the cracks and help prevent unintentional chipping or cracking. You can coat emeralds with baby oil as an extra care precaution to help the stone from becoming overly brittle.
The photo is of a Trapiche Emerald