Riverstone Flat Grey Pebble Sheets from Tile Trends. Colours available: natural, black, white, brown and ice. Materials: Natural stone flat pebbles. Dimensions: Interlocking 10x100cm strips and 30cmx30cm sheets. Frost proof. (www.tiletrends.co.nz) Stones like this are a great way to introduce a rustic twist into a space, while still allowing it to appear fresh, modern and stylish. This flat pebble sheet is perfect for an accent wall in the kitchen.