The male has a short almost straight bill with a black upper mandible, a lower mandible that is pinkish/red, and a black tip. The upper parts of the bird are blue-green and the under parts are rich blue with an iridescent violet throat. The tail is deeply forked with a blue-black color. The gorget is a glittering purple. The female and immature are not described (Hilty and Brown 1986).
The male Sapphire-throated Hummingbird L. coeruleogularis is found in the same habitat and can appear similar but lacks the glittering blue lower breast and belly.
Male: Crown, back, and rump shining green. Tail blue-black; the central rectrices are shorter than the outer rectrices, so the tail appears noticeably forked. The gorget is glittering purple; the remaining underparts are glittering blue.
Female: Plumages undescribed.
Maxilla black; mandible pinkish, with a black tip.
body length: 8.9 – 9.4 cm
bill: 18 mm
mass, male :4.3 grams