Among the many highlights of Roberto Cavalli’s 40th anniversary show yesterday in Milan was the runway debut of the ‘Diva’ bag. The purse comes in three sizes and seven materials ranging from denim to python to calfskin leather, so shoppers can easily find the right style for their wardrobe. “Women must never forget that personality is the most glamorous accessory of all,” said the designer.  Rachel Bilson and Taylor Swift both gave the bag their own personal spin, carrying versions to the show.  Want one of your own?  The ‘Diva’ will be available online and in stores in November and costs between $1,205 and $3,060.