WASHINGTON, DC (WUSA) -- Few purchases are as emotional as fine jewelry. But, shop with your head and you're less likely to overpay.

Consumer Reports Money Advisor Amanda Walker says you can get a great deal on jewelry and avoid costly rip offs.

"Fine jewelry is generally one of a kind, so you can't shop for the best deal like you can with a vacuum or a TV. So, you need to know what to look for, especially, if you shop online," says Walker.

So ask how pure is the gold in a piece, maybe it isn't even real. Gems like Emeralds, can often be enhanced by filling them with oil. And, over time that oil can leak.

A diamond can appear more brilliant through what's called fractured filling. But, this also makes diamonds more likely to shatter. So, you have to be careful when they're repaired and cleaned.

Walker says, "You should ask if a gemstone or a diamond is imitation, treated or synthetic. And, if the jeweler can't or won't tell you, that's your cue to shop somewhere else."

Buying gold, look for a karat mark. It indicates quality. And, a manufacturer's trademark let's you know whose work it is.

But the top tip for proctecting yourself, deal with a reputable company. Members of the American Gem Society must abide by a strict code of ethics.

You can go to to find a reputable jeweler in your area, not just where I am, but anywhere in the country," says jeweler Michael Wilson.

Whatever you buy, make sure you get the details in writing.

Experts also say you should consider an appraisal from a certified jewelry appraiser.

And, make sure the return policy gives you at least enough time to return something if it isn't what you expected.