I get to pick my Valentine's gift this year and this never happens. I need to decide between Tiffany's DBTY .17 necklace or the Cartier Diamants Leger Small. If anyone has comparison pics I would appreciate it. I was able to try on the Tiffany today but not the Cartier as I couldn't get an appointment in the boutique. Also, can Cartier lengthen the chain? I think it's 16 inches but I would prefer 17. Tiffany said they would. Thanks!