Re: Mosaic effetct tiles
They are rather cheap tiles and seeing as the grout lines are glazed and fairly shallow I would imagine, then I doubt you'll ever be able to grout the whole tile as you can do with some of them. Added to the fact they have a fake grouted edge to them, It's going to be neigh on impossible to make them look good, I would explain this to the customer and tell them "These tiles will never look like mosaics!"
I'd try and offer them a different tile, failing that i'd tile them with 1mm spacers and be done with it