Limescale on polished granite work surfaces - can I use Viakal / Limelight etc?

[Pennies]

If not, what can I use to get rid of it?

vinegar works wonders for me. Pour it on an leave it for a bit the scrub off with a pan scourer. Mind you my granite is black, so don't have to worry about marks. Don't think granite is porous, so shouldn't matter what you use on it, but if you have the light grey variety i would spot test some of the product where you don't see it - maybe under where you keep the cookbooks or the food processor.....