What to treat a stone fireplace with for color / contrast?

[Charlie MacPherson]

I'm working with a flipper who is almost done with a rehab I helped him to buy last year.  

The star of the show in this home is an ENORMOUS great room that's 750 sq ft.  The focal point there is an old stone fireplace which we just had sandblasted today.  100 years of crud and soot is now gone, but the stones look faded.

I'm guessing that there's some sort of coating we could apply to bring back the original color in the granite, but I don't know what that would be.

Any ideas?