A very good and competent body repair facility will be able to not only color match the needed paint to your existing factory paint but will also be able to reproduce the clear coat "sheen" - even if it's faded. Most Pro shops now have the ability to match new paint to existing vehicle paint, even if it is faded. It's amazing at how far paint technology has come along...
I had a 95 BMW M3 that was bumped in the rear by a small box truck. Luckily the only damage that occured was the rear bumper cover was scuffed along with the bumper cover trim moldings and the bumper shock absorbers. The car was factory Cosmos, which has metallic in it. The body shop who performed the work ordered all new BMW replacement parts and when the car was done, the paint job (paint color and clearcoat sheen) matched 100% perfectly to the existing body paint that had in excess of 90k miles on it. There was no discoloration, nor could one tell that the rear bumper was ever replaced or repainted when comparing it's finish to the rear quarter panels or the rest of the vehicle.
Best of luck with the repairs, it looks like an "easy" fix considering the damage that occured. Post up pics of your progress.
