Saint Laurent (or YSL or whatever your preferred moniker is) had a huge hit with their Arty ring, and they are now offering the Cassandre Monogram line, which is the Y, S and L initials entwined in rings and bracelets. They are available in white, gold and rose gold metal. So even though they deleted the Yves from the brand name, the initial stuck.
This cuff is gold tone brass, and approximately 42mm. It sells for USD$795 at Barneys.