Looking to invest? You may want to skip the safe haven options such as residential property and gold, and opt instead for art or wine. Knight Frank's Luxury Investment Index has risen in value by 5% over the past year, outperforming many house price indices and the bullion market, with the most coveted objects of desire appreciating by 25%. But it's not all been plain sailing. Bucking the upward trend, certain luxe collectables have been plummeting in value. We take a look at the top 10 risers and fallers.