Female Jamaican Mango is virtually identical to the male, only a bit paler below (slightly more greenish, especially on the flanks) and with pale tips to the tail. In other words, it is far darker than the bird on above photo and it would never show a pale greyish throat. Notice that juv's resemble females, so that's not a possibility either. I assume the confusion was caused by the rather poor description in "Birds of West Indies" by Raffaele et al (the description is not wrong, it's just rather unspecific leaving quite a bit of room for interpretation).
It's either a Vervain or a Streamertail. While I am hesitant to judge size on a photo like this I do think it appear too large for a Vervain (one of the absolutely smallest hummingbirds), but I could be wrong. Also, I think I can see a bit of red on the bill (unless it is a photographic effect from the feeder?) pointing in the direction of a female Red-billed Streamertail (all other Jamaican Hummingbirds always have a unicoloured black bill). Admittedly, the colour of the wing puzzles me a bit, but I assume that can be blamed on the usual iridescence that so often cause confusion in hummingbirds (BTW, the colour of the tail is fine). Regardless, unless the red bill or the size of the bird can be confirmed by the observer I will only call this a probable female Red-billed Streamertail, thereby leaving a bit of space for the other possibility; female Vervain...
