The Calla Lilly! Submerged Calla Lilly Centerpieces: I could also show you a couple of pieces with water pearls that might be a good idea. This is simple and elegant.
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.