Holiday Shopping -- eBay 101

— -- This report originally aired on Nov. 18, 2005.

Sue Paul has simple tastes, but she does like to shop. And like 80 million other Americans, she just loves eBay.

Paul said she generally makes low-cost purchases. "I stick with the small stuff, with a dish here or a cup there," she said.

Then Paul decided to try something different. Her daughter loved a Tiffany bracelet she had bought her over the summer, and Paul began looking for a sterling silver necklace to match it. Sure enough, eBay had one -- at least that's what the ad said.

EBay is the nation's biggest online auction site. Like regular auctions, whoever is willing to pay the highest price online when the auction closes, gets to buy the item.

Poised to get her daughter a Tiffany necklace, the low price made Paul even more excited to make the purchase. "It was like a third of what it was going for at the time, and I could knock her socks off," she said.

When the necklace came in the mail, her daughter's socks may have come off, but they would soon be back on. Paul said the necklace was slightly off-color, and she said the clasps were not as solid as you'd expect from the renowned high-end jeweler. Even the famous blue Tiffany pouch had a cheap feeling to it, she said.

We then brought her necklace to Tiffany's expert, who confirmed it was a fake. And it's not the only one. In fact, so many eBay sellers are pushing counterfeit Tiffany jewelry, that Tiffany is now suing eBay. The lawsuit came after the retailer's researchers found that almost three-fourths of all Tiffany jewelry sold on the eBay are knockoffs

"20/20" bought 16 new pieces from five different sellers (including the one who sold Paul her necklace) who advertised the items as Tiffany jewelry on eBay.

When we brought our purchases to Tiffany's experts, they told us only one of the items was authentic.

Of course you can legitimately sell used Tiffany on eBay, but jewelry expert Antoinette Matlins says that's it. You're not going to find new Tiffany items on the site, because there's no Tiffany discount retailer out there.

"The only people who can sell Tiffany jewelry is Tiffany," Matlins said.

Since Tiffany says Paul's bracelet was fake, we went to Indiana to try to track down Kevin Morris, the man who sold it to her under the Southbeachbodyjewerly name. Morris had a For Sale sign up on his house, and did not answer his door. He also wouldn't respond to our calls and letters, requesting an interview.

Master Gemologist Appraiser Neil Cohen said he is wary of buying pricey jewelry online."You can't tell the workmanship or anything when you're looking at a photograph," he said.