The advice here can help you get an idea of an object’s value, but for a true appraisal, you’ll need a written estimate by an accredited expert (see Appraisal ABCs), along with a detailed description of the methods used to determine the value.

Victorian Lamp with Hand-Painted Glass Globe

Backstory: Diane Winslow, 62, of Chevy Chase, Maryland, says her oil lamp, wired for electricity, sat in her grandmother’s house for as long as she can remember. The globe is not original.

What the Pros Say: “Known as a banquet lamp, this gilt-metal and onyx fixture was made in the U.S. around 1880 and is worth $900,” says George Evans, antiques expert and owner of Bond & Bowery, an antiques Web marketplace. Sheryl Muzzillo, an antiques dealer in Prospect, Connecticut, and Jim Antone, appraiser and owner of Pleasant Cove Antiques, in Jacksonville, Florida, both put its value lower, from $100 to $350. “Because it was converted to electric, and since the globe isn’t original, it wouldn’t appeal to a serious collector,” says Muzzillo.

The Verdict: Sell it. It’s unlikely to appreciate in value.