Worked out great.
Do It Yourself project with NuStair product: We used 12 x 12 ceramic tile cut in half to 6×12. They fit nicely in the 6 x 36 riser space with 1/2″ backer board behind them. There are 6 x 6 decorative tile every third riser. We installed all the tile risers by placing a 5/8″ spacer on the tread until the tile were set. The last step was to install all the tread.Worked out great.