Toting $30,000 of estate and antique jewelry -- emerald and sapphire necklaces, rings and pins -- gemologist Christine Krieger Brooks played consumer recently at seven Washington-area jewelers.

Her question: What would you pay me for these?

"I wanted to see what the consumer has to really confront," says Brooks, who selected stores that she knew bought antique and estate jewelry, based on her 12 years in the business. Although she anticipated offers of less than half the jewelry's worth, she was "appalled" at the responses.

"I knew it was bad, but I didn't think it would be this bad. I got prices ranging from $1,500 to $2,500. A good offer would have been $10,000-$12,000," says Brooks, 31, an independent gemologist/goldsmith/appraiser who has lectured at the Smithsonian.

Dealing with jewelry is analogous, says one industry person, to buying and selling cars.

"We're a self-regulated area," says Gerry Hansen, president of the Jewelry Industry Council in New York. "By and large this industry wants to give the most reputable product, but there is every kind of retailer out there."

The Jeweler's Vigilance Committee, founded in 1912, "to make certain that customers receive the products they believe they're receiving," has recently been inundated with calls about nationwide full-page ads promising diamonds that are actually cubic zirconia, or simulated diamonds.

"They're not diamonds, and they shouldn't be advertised as diamonds," says Joel Windom, president of the Jeweler's Vigilance Committee and former assistant attorney general of New York State.

The Washington Better Business Bureau, according to spokesman Marsha Goldberger, has requested that the company, Van Pler and Tissany, insert the word "counterfeit" every time it refers to diamonds.

Chase Revel, president of Van Pler and Tissany, says he plans no changes in the ads. "We're saying 'counterfeit' throughout the copy, and in 1-inch letters at the top. We've never had any complaints nor misunderstandings."

Whether you're buying, selling or appraising jewelry, the word is: Get educated first. Although jewelers acknowledge that consumers are more educated than they once were, a little knowledge, they say, can be a dangerous thing.

"Years ago, it used to be the romance and the beauty of the stone as opposed to, I want such and such color, clarity," says June Gianforte of Continental Jewelers, Connecticut Avenue NW. "People probably are a little more technical-minded than they used to be.

"The unfortunate thing is many times, while they're aware of terminology, people do not know what they're looking at. They will go from place to place with their little list in hand: 'This has a VVS2, I can get so much for such a weight . . .' Unfortunately, what they think they're comparing is not what they're comparing."

Sometimes just finding the right place to start can be confusing.

"Fluctuations in the market have bankrupted many family-owned jewelers," says James Rosenheim, 42, owner of the Tiny Jewel Box on Connecticut Avenue NW, who is concerned that the individual retailer is fast being replaced by mass merchandisers.

Hansen tells consumers to look for jewelers who've been around for a long time, and/or have qualifying credentials, such as a graduate gemologist degree from the Gemological Institute of America (GIA), New York, or the American Gem Society (AGS), Santa Monica, Calif.

But Brooks, herself a GIA graduate, suggests finding out even more about the person you trust your jewelry to. "One of the misnomers in the consumer's eye is that if you study at GIA, you know everything."

She suggests asking other questions: "What have they done in the industry? Have they worked in wholesale, manufacturing, selling? If they're an appraiser, have they worked with metal?

"When someone says they're an appraiser, I often ask, 'Have you ever made a piece of jewelry?' How could they know how to appraise a piece, if they've never made one?"

Shirley Belz, public relations director of the American Society of Appraisers, estimates 120,000 people nationally practice all kinds of appraising, but only one-fourth belong to any testing or certifying society, operating under a code of ethics.

Part of their code, for example, concerns the practice of charging a percentage of the appraisal price of a piece of jewelry.

"We consider it unethical and unprofessional to charge a percentage fee," says Belz. "The possibility exists to overcharge. The temptation is there. [They should] quote a flat rate, an hourly rate. This should be the first thing to ask -- how do you change?"

Washington real-estate and corporate attorney Warren Grossman, 40, had a 3-carat African emerald whose worth he estimated at $18,000 to $25,000.

"The jeweler looked at the ring and said $6,000. I said, 'Do you sell these stones?' He said, 'Yes.' And I looked in the counter and found a stone a carat smaller with less color and equivalent inclusions for $15,000.

"Most of the time they have very little incentive to give you a high appraisal," says Grossman, who ended up with an appraisal -- with a different jeweler and at an $80 hourly appraisal rate -- of $25,000 for his emerald.

"Appraisals are opinion," says Rosenheim, senior member of the American Society of Appraisers. "It's an ephemeral kind of thing, not like the value of a 1-ounce bar of gold."

"The minute you say value, you're talking about four different values -- retail, for sale, wholesale and replacement, which is what an insurance company would pay in theory to replace it," says Grossman, who deals "in an amateur way" with jewelry.

"The retail is discounted from replacement, the wholesale is what the jeweler would pay if he ordered it and the 'for sale' value is what he will pay you for it. It is so important when you say value that you communicate to the appraiser what you mean."

Jewelry as an "investment?"

"I don't think it's an investment," says Brooks. "I think it's for self-adornment and for those you love. When you buy it for that reason, you wear it and enjoy it. When it's for an investment, there's always that strange possibility that you're going to lose.

"The best you can hope for is what happened in '78 and '80. Your grandmother gave you a real pretty 3-carat stone; the prices went out of sight and you sold it then. You might make some money if your grandmother gave it to you or your mother gave it to you.

"But the best answer when someone says, 'Oh, this is an investment piece,' well, go out and try to sell it. And then see where your investment is.

"If you have a lot of money and you want to let the stone sit in a bank vault for 10 years, there's a possibility that you might make some money with some stones: a Kashmir sapphire, a Burmese ruby, a really fine, large-size oriental natural pearl -- something very rare. Then it's finding the customer that wants to buy it."

"I have people calling me frequently asking me, will I buy their diamond," says Louise White of Dikomey Jewelers, I Street NW. "I always tell them, look, you're going to get the most money if you can find an individual on the outside to buy it. Give them a little bit off. If the stone retails for $1,000, sell it to them for $750-$800. They'll be getting a buy and you're getting a good price."