Only the male plumage of Bogota Sunangel is known. Based on a single specimen, the male is medium sized hummingbird with a relatively short straight bill and a long, deeply forked tail. The body plumage is primarily dark bluish black, with a brilliant green forecrown and gorget, dark purple rectrices, and pale undertail coverts.
Male Bogota Sunangel is superficially similar to male Royal Sunangel (Heliangelus regalis), but differs by its green forecrown and gorget, dark purple (not blue) rectrices, and pale (not bluish black) undertail coverts. Other species of hummingbirds of the northern Andes with long, deeply forked tails, such as sylphs (Aglaiocercus) and trainbearers (Lesbia), are primarily green, not blue. The female of Bogota Sunangel is undescribed.
The following description is based on Graves (1993), and refers to the unique holotype:
Adult male: Lored, auriculars, and crown glittering steel blue. Forecrown pale golden green. Small white postocular spot. Nape, back, and wing coverts deep bluish black, slightly iridescent, becoming deep greenish blue on the lower back and rump; the uppertail coverts are bluish black. Rectrices dark glittering purple on upper surface; under surface duller and less iridescent. Tail deeply forked. Remiges dark brown with a purplish tint. Underparts duller than upperparts. Chin dull bluish black. Gorget brilliant golden green (the same color as the forecrown), bordered posteriorly by lustrous bluish black. Upper breast bluish black, feathers with narrow buffy gray margins; paler on the lower breast and belly, the center of the belly medium gray. Sides and flanks dark bluish black. Undertail coverts pale creamy white. Tibial feathers dull grayish brown.
Adult female: Undescribed.
Unknown in life. The bill of the holotype is black; the scutes on the toes are brown; and the toe pads are yellowish brown (Graves 1993).
Total length: 11 cm (McMullan and Donegan 2014)
Linear measurements (from Graves 1993; n = 1, male, holotype):
wing length: 66.8 mm
bill length: 15.1 mm
tail length (outermost rectrix): 64.8 mm
tail length (innermost rectrix): 30.1 mm