Updated for stock price trends.NEW YORK ( TheStreet) -- Are the luxury retailers that have held up so well during the slumping economy finally starting to show cracks or can they still power through tough times? As the ICR XChange conference kicks off in Florida today, some retailers are providing earnings guidance updates ahead of scheduled presentations. At a glance, the pre-announcements have been mixed. Of most interest was the divergence in high-end retailers Lululemon ( LULU) and Tiffany ( TIF). Better-than-expected sales at Lululemon drove management to raise fourth-quarter earnings guidance in a big way today, while lower-than-anticipated sales at Tiffany led to a worse outlook. So far Tiffany's stock is trading down 11% today and Lululemon is trading up almost 12%.