An emerald is an emerald is an emerald?

Maybe. Maybe not.

Newspaper readers around the country wondered as they were confronted in recent weeks by advertisements offering a "genuine emerald" for only $5.

"Each stone is a genuine emerald," read the full-page ad in the Aug. 17 Washington Post, "accompanied by our Certificate of Authenticity to that effect."

Signed H. M. Fisk, Jericho, N.Y.

The copyrighted ads, carried also by the Miami Herald, New York Times, Los Angeles Times, New York magazine and other publications nationwide, prompted numerous calls from curious readers and probes by better business bureaus and consumer affairs offices in almost as many cites.

All asked, "Is this legit?"

Maybe. Maybe not.

"It's the worst junk you'll ever see," said Haig Kanjian of the Permanent International Jewelry exhibit in New York, an organization that assists in completing gem transactions on a global scale. "It's not the kind of thing you can set in a piece of jewelry."

Several gem experts, government officials and at least one magazine executive who thought the offer suspicious commissioned appraisals to find out if the stones are what the ad claims they are.

Maurice Shire, one of the country's leading emerald importers and a board member of the Jewels Vigilance Committee, an industry oversight group, took some of the stones to the Gemological Institute of America for scientific evaluation.

"According to what we've seen, some should technically be called emeralds," said an institute spokesman. "It's a little unfortunate that this possibility exists. The raw materials are virtually worthless."

Experts theorize that the emeralds sold by H. M. Fisk are imported in huge quantities from mines in Brazil, "in plastic bags of 15,000 -- like frozen food," said one. They believe the stones then are taken to India to be cut by persons paid at sweatshop rates.

Apparently, all of the stones are beryls. But not all beryls are emeralds. To be an emerald worthy of the name "gem," a beryl must show a green hue, caused by trace amounts of chromium, said Paul Desautels, curator of the Smithsonian Institution's extensive gem collection. According to the institute test, Fisk is offering a mixed bag. Some stones have enough chromium green hue to be called emeralds. Others are just beryls.

"In either case, it would not be acceptable to a jeweler for his stock," said the institute spokesman. "There's no other use for these stones. Except maybe at the bottom of somebody's fish tank. They're pretty."

Some appraisers refuse to place a value on the Fisk stones. Others say they are worth perhaps 30 cents or 50 cents; still others appraise them at $1 or $2. "I would suggest that anyone who buys an 'emerald' for $5, $10 or $15 is probably buying a stone that will retail for $5, $10, or $15," said Desautels.

"He's selling something that is worth about one penny a carat," said Shire. "God forbid there would be worldwide depression and I could understand people paying $5 for them."

And what says H. M. Fisk?

H. M. Fisk doesn't say anything. He doesn't exist.

Some of the emerald ads include a picture of a middle-aged man with shortish silver hair identified as H. M. Fisk. Sometimes he has a beard. Sometimes he is clean-shaven.

But he doesn't exist. H. M. Fisk is an assumed name. The pictures of him are known in the trade as "dummies."

As a person who doesn't exist -- a free spirit, you might say -- Fisk can live wherever he pleases. Some of the ads give his address as a post office box in Jericho, Long Island. In other ads, his address is 208 W. 38th St., New York City.

The address in Manhattan belongs to a tobacco store called Stevens Smoke Shop. The smoke shop is run by Lou Hyman, who, besides cigars, also sells H. M. Fisk emeralds in plastic boxes over the counter. Hyman collects the newspaper coupons, clipped from the ads and mailed to his address, in shopping bags and forwards them to a location on Long Island.

Stevens Smoke Shop is the retail outlet for Jay Norris Corp., a national mail-order company, operating out of a warehouse at 31 Hanse Ave. in Freeport, Long Island.

Jay Norris Corp. is appealing an order by the Federal Trade Commission to mend its curious business ways. The FTC believes Jay Norris Corp. has a history of false and misleading advertising practices.

The FTC has cited Jay Norris and related companies for misrepresenting at least six different products. The companies are involved in selling toenail clippers, bicycle pumps, "collector's" coins, TV antennas, roach powder, cheese and now emeralds.

The sole owners and shareholders of Jay Norris Corp., Joel Jacobs and Mortimer Williams, are also officers of Federated Nationwide Wholesalers Service, Garydean Corp., P-N Publishing Co. Inc. and Pan-Am Car Distributors Corp.

And Jacobs is the secretary and Williams is the treasurer of H. M. Fisk. The president of H. M. Fisk is Stephen Brown. Stephen Brown is also the president of Gem Collectors International Ltd.

In February, the Illinois attorney general's office filed suit against Gem Collectors International Ltd. because of ads in Parade magazine and Family Weekly purporting to sell "genuine diamonds" for $8.95 per half-carat.

The ads showed a lustrous gem. A real beauty. In fact, said assistant attorney general Bill Oberhardt, the product looked more like "dried airplane glue."

The "genuine diamonds" were rough industrial stones with very little resale value," said Oberhardt. On June 22, Gem Collectors International Ltd. filed a consent agreement requiring the company to send letters to 900 Illinois customers offering a 100 percent refund.

Jay Norris' trouble with consumer watchdogs goes back to 1975 at least. In September of that year, the FTC filed its order charging that the officers of the company, among other dubious business practices, "failed to live up to advertised promises of immediate delivery and prompt refunds . . . "

Five-dollar emeralds?

Fisk attorney Robert Ullman, who acknowledges the interlocking directorships of the many companies at 31 Hanse Ave. with a sprite "so what?" says an unknowing jeweler appraised one of the stones as being worth $50.

"Hell," Ullmann said, "the company pays a buck each for them."

But he won't release the name of the jeweler who performed the appraisal.

The Better Business Bureau in New York thinks H. M. Fisk, whether he exists or not, is up to no good.

"We feel (the ads) do not meet with our standards," said the manager of the bureau's mail-order department, Matthew Opperman Jr.

The bureau issued a report Aug. 15 condemning the ads, saying they misrepresented the stones by using such words as "certified," "vaults," "authenticity" and "notarized."

The so-called "Certificate of Authenticity" that accompanies the stones is issued by H. M. Fisk.

The ads have also piqued the curiosity of the U.S. Postal Inspection Service, which is starting an investigation of its own. The New York Attorney General's Office is making inquiries, and the New York City Bureau of Consumer Affairs is advising readers not to send away for the stones.

But that's not stopping the nation's top publications from running the ads.

"We presume innocence," said New York Times advertising acceptability representative Bernard Stein. J. Morton Williams Inc., the in-house ad firm that represents H. M. Fisk and the various 31 Hanse Ave. accounts, has placed ads with the Times on several occasions.

(A full-page ad, such as the one Williams Inc. ran for Fisk in the Times in July, can cost more than $15,000. Because Jay Norris Corp. lists Stevens Smoke Shop as a retail outlet, however, Williams Inc. can receive ad space locally for almost half the cost, said a Times source.)

"We assume our readers are getting a fair shake when the ads are presented to them," Stein said. "If other facts come to light and are substantiated, then we will look at our position. But just because a company is being investigated by a government agency doesn't mean we can't carry their advertising."

"We have had business from Fisk in the past and we've always been paid," said a spokesman for New York magazine, where a recent Fisk ad would normally sell for about $3,500. "We've never received any complaints regarding clients of J. Morton Williams."

Says Robert Martin, customer relations manager at the Washington Post: "There's nothing wrong with the ad itself. The information in it is correct. We leave it up to individual readers to decide if they want to send away $5 for 50 cents worth of emeralds."