Small, and all dark-green, the males are easy to identify. When head on, they flash a startling glittering golden-green. The much more infrequently seen females or immatures are pale gray below with a broad white stripe behind the eye, a pattern similar to the Speckled Hummingbird. Speckled is larger and bulkier, with speckles on the breast and throat. If treated as separate from the almost identical Blue-tailed Emerald, found east of the Andes, the Western Emerald is a Chocó endemic.

male