Designer handbags have few commonalities, regardless of brand. Portero's Director of Accessories, Elizabeth Bernstein, says to check the inside seam for a date stamp, which is a leather or paper tag indentifing the product as authentic. If you can't find this, look for a hologram sticker with the brand's logo.
If you do a little vintage investigating, you can learn excatly what a company's hologram or stamp looked like each season. If it's a current model, "visit the store and look at the real thing," says Elizabeth.
Request as much information as possible from the vendor; if you can, look at the dust bag, authenticity card and original box before buying. Much like belts, stiching and hardware are also important. Knowledge is power! So be sure you know what to look for.