(IDEX Online) - Prices of used Rolex, Patek Philippe, Audemars Piguet and other luxury watches are sliding.They were down 6.7 per cent in November according to the Subdial50 Index, which tracks prices for the 50 most traded luxury watches.Among the biggest losers were the Rolex Oyster Perpetual 41 Reference: 124300, down 10.8 per cent to $8,283 and the Patek Philippe Nautilus Reference: 5712/1A-001 down 10.3 per cent to $104,524.The index, compiled by the UK-based reseller, shows prices for every one of the top 50 watches falling in the 30 days to 2 December.Pic of Patek Philippe Nautilus Reference: 5712/1A-001, courtesy Patek Philippe