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.
Pretty idea but please use battery/flameless tea lights and not actual candles. Plastic spoons will melt and rose petals are flammable. DIY Flameless Rose Tea Lights: so pretty for a wedding table, tea or brunch.