looks like rex cv. 'Supercurl' or 'China Curl,' which will not take direct sun at all.

rexes do tend to get duller if they aren't given sufficient light levels. have you considered an overhead grow light? an aquarium bulb is enough, sometimes. it makes sense that a plant would produce more green chlorophyll if light levels drop below what it has been used to. my 'Stained Glass' is now reddish grey as opposed to the brilliant sparkly red it was when i bought it. i've moved it to a brighter spot, though, and it's starting to color up.

-ming

thank you for the info. the begonia will be outside on a porch so it will get sufficient light. i looked at the begonias again at the garden center and it appears that the little hairs on the surface pick up the sunlight and help give it the sivery appearance. the begonias are actually more greenish than when i first looked at them. it's still pretty tho.