Emerald is an autosomal recessive mutation, this mutation heavily reduces melanin throughout the plumage, but retains a dark head and rump. The visibility of the yellow psittacin pigments in this color morph is due to the reduction of the melanin pigments allowing the yellow to show through. This mutation is purely a melanin-altering mutation. 

This mutation was established in the United States of America around the 1980’s and is currently widely available around the world.

There has been confusion between the Australian Olive mutation and the American Emerald mutation, Emerald clearly shows reduced melanin pigmentation in the soft tissue that darkens with age which also indicates that this is not a true suffused mutation, as with the Olive mutation the eyes, beak and feet remain normally colored as a true suffused mutation would display.

It is considered undesirable to pair Emerald to melanin altering mutations such as Cinnamon, Bronze Fallow, Lutino , Recessive Pied, Dominant Silver, Olive and Opaline as these mutations would mask this mutation and make it difficult to identify which melanin altering mutations a bird is carrying.