Cast Stone Fireplace - HELP
 

I have a cast stone fireplace mantle (looks like limestone), and has
some intricate carvings in it.
Well, it was installed very sloppily by the mason.
They didn't leave an inch in the mortar joints to add grout to match
the actual color of the stone. So, I have grey cement in the joints,
and they even got some cement on other parts of the stone.
It makes the stone mantle look sloppy and you can see all of the grey
joints. The stone should look uniform, and all one color.

I need an opinion on painting stone.
Can I just get a spray can of tan (stone looking) paint and paint the
whole thing to make it look uniform? I tried it on a small section and
it looks ok.
I am worried that if the stone get's too hot from the fire, that the
paint could light up?? Is that possible once it has dried?
After the paint, I would also like to seal it for easy future clean up.
Please give me any suggestions you may have.

Thanks in advance.