PUMP IT UP: Hollywood really does have a heart.
     Some pretty big stars such as Kristin Davis ("Sex and the City"), Tara Reid ("American Pie"), Thora Birch ("Ghost World"), Megan Mullally ("Will & Grace"), Cameron Diaz ("Vanilla Sky"), Drew Barrymore ("Riding in Cars With Boys"), Gwyneth Paltrow ("Shakespeare in Love"), Courteney Cox-Arquette ("Friends"), Marcia Gay Harden ("Pollack"), and singers Jewel, Britney Spears and Faith Hill tried their hand at designing one-of-a-kind heart necklaces for the Platinum Guild's new Women With Heart program. All proceeds go to the stars' favorite causes.
     Four of the guest jewelry-makers — Birch, Davis, Harden and Reid — turned up Wednesday night at Sotheby's in Beverly Hills to help auction off their designs. At first, the bidding was fast and furious. Candy Spelling watched with delight (with husband Aaron and daughter Tori nearby) as her delicate double-heart design necklace fetched $5,000 to benefit the John Wayne Cancer Institute. Renee Zellweger's heart with the word "grateful" in the center fetched an impressive $5,500.
     But Davis' curved heart pendant with pave diamonds and Burmese rubies garnered a whopping 9 grand for the New York Police and Fire Widow and Children's Fund. She was joined by New York City firefighters Steven Hardwick and Michael Cortes.
     "I wanted my heart to be as bold as they were and to show our hearts have all grown since that day and how connected we are," Davis, wearing an elegant black gown, said.
     Even if you couldn't make it to Sotheby's to snarf the ritzy snacks — crab puffs, radicchio salad, tender wrapped meat nibbles — and sip bubbly on the open-air patio, you can still have a heart. The bidding continues online until Feb. 15 (www.preciousplatinum.com and sothebys.com), where you can bid big for Britney's briolette diamond heart, or Jewel's intertwined hearts (one jeweled, one matte) or Birch's double-heart design with a 1-carat diamond that she wore to the Golden Globes.