I don't know exactly what a chokecherry is, but regarding the variation (it IS pretty): a) it will probably have to be vegetatively propagated (cuttings) b) you will probably have to vigilantly pinch off normal leaf sprouts/vines, and c) the varigation may be produced because of a virus.
I say that because in Holland, when they had their big tulip bulb bust, the varigations were virus caused (today they are not) but sometimes I see varigated wild (?) mustard, and it does not looke quite right.
On the other hand, you may have a valuable plant!