Crimson topaz

The male crimson topaz is 21 to 23 cm (8.3 to 9.1 in) long including the 5 cm (2.0 in) bill and 8.6 to 12 cm (3.4 to 4.7 in) tail, and weighs 11 to 18 g (0.39 to 0.63 oz). Females are 13 to 14 cm (5.1 to 5.5 in) long and weigh 9 to 12.5 g (0.32 to 0.44 oz). It may be the second largest species of hummingbird after the giant hummingbird, rivaled only by its cousin, the fiery topaz.

Male and female crimson topaz have different plumages. Both have a straight to slightly decurved bill. The male's head, face, and the sides of the neck are velvety black. Its back is iridescent crimson to gold on the uppertail coverts. The central tail feathers are bronzy green and the outer ones chestnut; two of the latter are elongated and crossed. The throat is golden green surrounded by a black band and the underparts bright red. The wings are brown. The female's head and back are dark green and its underparts a lighter green with golden green inclusions; the throat is green with crimson inclusions. The central tail feathers are bronzy, the middle pair violet, and the outer pair chestnut, and none are elongated like the male's.