I have also seen similar centerpieces that use epsom salts instead of sugar. You could also sprinkle a mix of pearls/gems. Sand (or sugar), faux pearls, a 3 candle. An easy DIY wedding centerpiece idea.
Candle table centerpiece (inspiration only) Glue fake flowers to the bottom of a tall vase (or to stones you could drop in), fill with water, and top with a floating candle. This is a really cute idea for center pieces!