Owner Marc Watts and manager Robert Carlson of Gaithersburg Coin Exchange, one of the largest dealers in the East, offer these reminders to anyone considering selling coins, jewelry, flatware, dental gold, whatever:

A 10-karat gold ring is only 39 to 40 percent gold, so if the price is $700 per ounce on the spot market in New York, the price would be roughly 40 percent of that. (Most class rings are 10 karat.)

If scales are in full view, you are more likely to get a fair deal. (It is possible, however, for a buyer to tinker with scales and calculations.)

Phone estimates are valid only for dated coins. Gold have to be tested and weighed to be priced. "No one," says Carlson, "can offer a firm price over the phone without knowing the exact weight in grams or pennyweight."

Sterling is always marked sterling, or has a British hallmark. Silverplate is determined most satisfactorily by filing the underside of an object and applying a drop of nitric acid on that spot. (If it turns green, it is not silver.)

Counterfeit class rings -- containing not a gram of gold -- are now being peddled on the market.

The only way to be assured of a top price is to shop for it, by checking many dealers.