Diamond customers have a few things to remember

NEW YORK -- Whether you walk into a jewelry store with visions of chandeliers or wedding bells, it pays to educate yourself about a girl's best, and most expensive, friend.

The Diamond Information Center, an organization that promotes the diamond industry, says diamond consumers should go to school on the "four C's." That's color, clarity, cut and carat -- how a diamond measures up on these four criteria determines its value.

Carat denotes the size of the ring, but is only one criteria, and thus two rings of the same size can have different prices. The quality of the cut is what makes a diamond reflect light and produce a brilliant sparkle.

Clarity refers to blemishes within the stone, or inclusions. The rarer stones have fewer inclusions. Diamonds with the most inclusions are graded I1 or I3, and the stones with the fewest inclusions are VVS1 or VVS2. Color is more of a personal choice, since any diamond color can be cut brilliantly. But the rarest, and priciest, stones are either in the most colorless range or are brightly colored "fancies" in such colors as pink, blue and yellow.

To make sure you are working with a reputable dealer, the Jewelers of America, (800) 223-0673, can make recommendations. Major purchases often are accompanied by diamond certificates or diamond grading reports provided by the American Gemological Society, the International Gemological Institute or the Gemological Institute of America.

Once the purchase has been made, don't forget that diamonds require upkeep. Daily buildup of skin oils and soap can dull diamonds. To keep your jewelry sparkling, the Diamond Information Center suggests regular cleaning by any of the following methods:

Give your jewelry a yearly checkup and bring it in for a professional cleaning by a jeweler, who can also check for loose fittings and other potential problems.

Soak jewelry for 30 minutes in a solution that is half cold water and half household ammonia. Then use a soft brush to clean the jewelry before giving it a second rinse in the solution and letting it dry on a paper towel.

Give your jewelry a "bubble bath" in a bowl of warm water with a small amount of any mild liquid detergent. While it is soaking, use a small brush to clean the jewelry. Then put the jewelry in a strainer and rinse with warm water under the faucet and pat it dry with a soft, lint-free cloth.

Over-the-counter jewelry cleaners are another option, and your jeweler can recommend which one is right for you.

Ultrasonic cleaning uses a machine to clean jewelry with a high-frequency vibration. A professional jeweler can do this, or you can purchase an ultrasonic cleaner and do it at home.