The Purple-throated Mountain-gem is a striking hummingbird, where the male has a brilliant, iridescent throat the turns purple. The crown also changes color, from dark purple to metallic blue, all due to the angle of light that is hitting it. The upperparts are mainly green, although the belly is gray and the chest has a broad metallic green band as well. The female is similar but has a cinnamon belly, chest and throat, which does make it look very contrasty and eye catching. Both sexes have a white postocular line that reaches down and back almost to the neck. They are mostly seen in mid elevation cloud forests.