The first thing swimming-pool tile specialist Gerard Arriola tells clients: Tiles never look the same in water as they do on land. "It's rather difficult to foresee the effects of the pool-water color by just seeing the tile," Mr. Arriola says. "Other elements like lighting, location and shadows are crucial factors in the outcome."

Mr. Arriola and his wife, Janie Phee Eng Choon, who are based in Singapore, own Ceramica 28, which supplies high-end swimming pool tiles. Typically, they work on 16 to 25...