@midlife has a good suggestion you could also try getting a grout rake and raking out the horizontal lines between the tiles and re-grouting with a light grey or cream grout that is closer in colour to the mosaics.
If you put tiles on top of tiles like you are suggesting you are inviting water penetration problems down the line.
@midlife has a good suggestion you could also try getting a grout rake and raking out the horizontal lines between the tiles and re-grouting with a light grey or cream grout that is closer in colour to the mosaics.
If you put tiles on top of tiles like you are suggesting you are inviting water penetration problems down the line.