they sell plate hangers that actually attack to the plate to hang them on the wall. I got some at Pier One or maybe a place like Bed, Bath and Beyond??? Not sure about the sculpture. Without seeing it I'm not sure what to suggest.

I use plate hangers for my tiles (even a 12"x12" granite) they hold up to 30 pounds and the largest one I use is 10"-14". Works well. Found them at Wal-Mart, Lowes and Home Depot...

Thank for posting this query on Garden web. I have a similar problem with a beautiful artifact which hangs to a wall. Recently my two year old hit it with a ball. It came flying onto the ground. when i retrieved it i found that the back hook that helps in hanging on the wall has come off. I am looking for some help on the net. I found your query an suggestions to it. Really a great help.