Bird Watching: Hummer ID help please, 1 by TXSkeeter

TXSkeeter wrote:
This little jewel has been guarding the hummingbird feeders in my yard for a couple of weeks now but I can't decide if it is a Ruby-throated (very common in DFW) or a Black-chinned for which we are on the very eastern edge of their range according to my 'Sibley Guide to Birds'.
The throat has a definite purple sheen even in changing light compared to the Ruby's typically red throat.
Any ID help would be appreciated...
Steve