Hugh Hefner's wife Crystal Harris is auctioning off her wedding dress and shoes to raise money for a cancer charity in the name of Hugh's late secretary Mary O'Connor.The Playboy Playmate has decided to sell the gown and shoes she wore when she tied the knot with Hugh Hefner on New Year's Eve (31.12.12) and all the proceeds will go to the Leukemia and Lymphoma Society charity in the name of Hugh's long-time secretary Mary O'Connor, who died last weekend.Crystal wrote on Twitter: "I am auctioning my wedding dress with @charitybuzz to raise money for lymphoma in memory of Mary (sic)"The 26-year-old blonde beauty also included a link to the website www.charitybuzz.com where individuals can bid for the dress.The details of the lot read: "This is your opportunity to own Crystal Hefner's stunning wedding gown and shoes from her recent wedding to Hugh Hefner!Â "Crystal and Hugh tied the knot on New Year's Eve in an intimate ceremony at the Playboy Mansion. The gown is a strapless, floor-length mermaid-style in soft pink by Romona Keveza, and the shoes are designed by Aruna Seth."Crystal is donating this dress in memory of her good friend, Mary O'Connor. Mary was Hugh Hefner's long-time assistant of 40 years, and is credited with helping Crystal reconcile with Hef last year, ultimately leading to their recent wedding. Money raised will benefit the Leukemia and Lymphoma Society in Mary's name."The items are valued at $7,500 and the top bid currently stands at $1,000. The auction ends on February 11.Mary worked as Hugh's assistant for over 40 years and is credited with helping Crystal get back together with the 86-year-old Playboy owner after she called off their original wedding.Â Hugh - who described Mary as "the rock" of the Playboy Mansion - said: "It's Mary O'Connor that brought Crystal back. Crystal was miserable and said so. Mary told Crystal to write and tell me, which she did."