Video More Video CNN's Gerri Willis shares five tips on what you should know before you step into a jewelry store. Play video

NEW YORK (CNN/Money) - You're in deep. Cupid either just struck you silly or hit you years ago so hard those feelings are still there. Nonetheless, the little chub has you out looking for a diamond, ruby, or sapphire or maybe all three to express your love for that special someone this Valentine's Day.

While you might be smitten, wise up there. Precious stones are a big-time purchase. To make sure you're getting the real thing and the best rock(s) for your buck, don't count on the salesman. In today's top five tips, get ready for boot camp for buying gems.

So you don't know a thing about diamonds, or rubies, or whatever. You're just like the three out of four men who say they do not feel knowledgeable about buying jewelry, according to NPD Research.

The first thing to get out of your head: Forget about keeping up with the Joneses. Buying jewelry for someone is a personal thing, not a competition.

If you have no idea what she wants, remember she probably knows exactly what she wants. Turns out that can save you some serious money. When guys buy jewelry alone, they spend significantly more than when she's involved, according to John Baird, Blue Nile's engagement ring and jewelry expert.

You men are sweet to buy a gal something really huge out of the fear of being inadequate. But trust me, it's not necessary. Get her involved in the process. She will get what she wants and you might get a bargain. If you must surprise her, at least go in with a budget in mind and find the best stone that meets it.

The 4 C's is jewelry talk for cut, color, clarity and carat -- or weight. Stanislas de Quercize, president and CEO at Cartier, says these are the qualities in a gem that are used to determine its value.

According to de Quercize, the cut, which refers to the stone's angles and proportions, is what counts most. Even if a diamond has perfect clarity and color, a poor cut can make the whole rock look dull.

The best cut out there is called an ideal cut. Several jewelers will actually brand their cuts. Cartier has one called the Starburst; when you look into it, it's like looking into a kaleidoscope.

How do you know what the 4 C's are for your specific stone? Get the 5th C: Certification. Baird advises, "Only buy a [stone] that is certified. It's a way to protect yourself from being ripped off."

Independent gem labs evaluate stones for their quality before they ever land in their setting and are put on display. Any stone you consider should have its own certification.

Ask to see it before you purchase the jewel. Some stores try to say they can't get it for you until six weeks after the sale. That's just to keep you from seeing the truth behind your stone's quality.

Certified gems might cost you more, but Baird says it's worth it because a major gemological institute has guaranteed their quality. The gold standard for certification come from the Gemological Institute of America (GIA) and the American Gem Society Laboratories (AGS). Check out AGS' Web site at www.AGS.org for a consumer guide to buying diamonds.

A nicely cut and certified gem is going to be perfect no matter what because it expresses your love. But if you're worried about price, there are a few ways to cut corners.

For one, you can go shy with the weight. Baird says prices on diamonds in particular jump at the carat and half-carat marks. So consider trimming the fat a bit on that 1-carat diamond and go with the 0.95-carat one instead. The only difference you'll notice will be in your bill.

Another idea: leave a little color in your diamond. The naked eye can't see the difference between flawless and near-colorless. Save yourself some cash and keep a little color.

This is Top Five Tips, so of course I'll tell you to shop around. There is an array of places to buy jewelry.

Think about what matters to you most. Shopping for a brand name might add a premium to your tab. If personal service and reputation is important to you, go a luxury store such as Cartier.

If this is a gem for your engagement, and you will need wedding rings soon, consider building a relationship with a trusted family jeweler, who might offer you a nice deal for your continued patronage.

If you shop online, check out www.BlueNile.com. Since Blue Nile cuts costs by being online and by cutting out the middleman, its prices are often 20 to 40 percent less than a luxury jeweler's.

Gerri Willis is a personal finance editor for CNN Business News and the host for Open House. E-mail comments to 5tips@cnn.com.