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.
Beautiful center pieces or just around the house- rocks, flower of your choice (maybe string it to a rock by the stem so it doesn't float) in a vase, fill with water, add small candle and voila-on the mantle?