They're from http://kitmiles.co.uk/ :) I LOVE them, so I need my fireplace to match :)

From a practical point of view:-

Obviously you can put what you like on top of the hearth, tile straight over tile on tile, but you'd need to make a surround as you'll see the edge. I'd make sure that your hearth tile isn't going to clash or look wishy washy against the white skirting and the marble of the actual fire surround.

Also, as I see it's a working fireplace, if you go for something very light on the hearth, the grout will be filthy within days. You also couldn't go for a tile with a porous surface as this would lead to the tiles themselves also getting dirty. You'd either have to seal the surface of the whole hearth to make it cleanable, or go for a shiny surface tile & somehow seal the grout to keep the soot of it. Once on, never off. This is why hearth's are usually grey / black with grey grout. I'd keep the hearth as is, because it matches the fireplace and is a practical colour.

With regards the tiles on the fireplace, they are inserted from the back of the fireplace in to a frame not visible from the front. The only option you have without taking the fire out is to tile on top of those tiles. You will then get the same problem with seeing the edges as you would if you tiled the hearth. You can buy thin 'pencil' edges to possible combat the problem such as these from B&Q Pencil Trim you just need to put your tiles in between them. It all depends on what the tile surface is like and where the originals butt up to the cast iron.

Maybe you would be better off with fire retardant tile paint for the fireplace tiles.

Hi Jeni. I think the colours in the tiles pick up the cushions perfectly. If im honest I wouldn't change tiles to match cushions which have a very short shelf life anyway. Why not paint the chimney breast the dark olive green? You've also got a green in the tile. If the hearth needs upgrading I'd go for black again

I agree with Minnie. if the cushions are your main source of inspiration I would also paint the fireplace wall. I have just painted a wall in Mouses Back Farrow and Ball and it looks stunning and reads as slightly olive.