On 30 June, 13:58, Kevin wrote:
There's large gaps behind the black granite upstands where the walls
aren't straight.
Ideal solution is to reskim the wall to level it off, but this isn't
going to happen. We've decided best compromise is to use some black
filler, but I'm not sure if black caulk exists and I'm a little wary
of using silicone.

following on from Fred's link - this:-

Stixall M.S Polymer 290ml Black (fromToolsatan)

dries shiny - it may just be the ticket?

cheers
jim