In the revised classification to create monophyletic genera, the berylline hummingbird was moved by most taxonomic systems to the resurrected genus Saucerottia.

Adult males of the nominate subspecies S. b. beryllina have a bronze-green to coppery head, back and rump.

[9] Subspecies S. b. viola has a grayish tinge on its back and rump, a fawn to cinnamon belly, and dark violet uppertail coverts and tail.

S. b. sumichrasti males have duller green plumage than the nominate and a purplish gloss to the tail.

It increasingly has wandered and sometimes bred in southeastern Arizona and has occurred in southwestern New Mexico and western Texas.

[9] The berylline hummingbird is a generalist, foraging for nectar at a wide variety of flowering plants both native and introduced.

Though it will congregate with other hummingbird species at flowering trees, it tends to be dominant over most and often defends feeding territories.

In addition to nectar it feeds on arthropods captured by hawking from a perch or picking from spider webs.

It makes a solid cup nest of grass and other plant fibers bound with spiderweb with lichens on the outside.