Used this as trim inside my shower with the marbled pencil trim. I used Carrara porcelain tile. Don't be afraid of mixing materials. This is carrara with ceramic subway tile. The pencil helps deal with the possible thickness differences.
Rather than having a tall accent, simply cut this sheet containing 10 columns with 10 rows into 5 rows of squares, or 2 rows of squares. Your accent strip will be smaller, but you'll save a lot of money here.