It's a place where men walk around with a quarter of a million dollars in their pockets, where six-figure deals are negotiated on sidewalks in Yiddish and sealed with a handshake called a mazel.

It's all of one block long, the New York diamond district. Yet within any given year, almost half of the world's diamond trade occurs there.

It is also a place where you can lose more than your shirt. Eight New York diamond dealers have been murdered since 1974. Within the last three weeks, one man was found dead, another disappeared and is still missing under suspicious circumstances.

To the New York police, it's like Chinatown -- a baffling, ingrown world steeped in family tradition whose arcane structure bars inquiries into its internal affairs from the outside world. into its internal affairs from the outside world.

To the people who work in the district, publicity is an anathema that invites the fate of those eight dead men. That is why it is hard for the uninitiated to remember just what there is between Fifth Avenue and Avenue of the Americas along 47th Street.

"No names," says a retailer of 20 years. "That's just telling the criminals where the diamonds are."

These men and women live a world away from their decidedly distant cousins around the corner on 5th Avenue. There, international diamond meccas such as Harry Winston, Cartier and Tiffany cater to people who talk softly and enjoy two-digit carat stones.

Those are the kinds of places that convince you you've got a piece of spinach stuck in your teeth, where you can hear a pin drop onto floors that are wired with sophisticated alarm systems.

The customers of the 47th Street retailers, on the other hand, are more apt to look for inexpensive wedding rings on installment plans.

"Forty-seventh Street does have an image of schlock, of high-pressure thieves," concedes Bruce Kamm, a second-generation diamond wholesaler and retailer. "I don't want to mention names, but I know of a guy who owns about four stores under different names here. He has been indicted six times for painting diamonds."

Customers may browse first through the International Diamond Exchange at the corner of Forty-seventh and Fifth, where small independent dealers hawk their goods from cramped booths. The hard sell is used there in half a dozen languages, as are a stylized negotiating technique and a fair amount of pandemonium.

It is on the tables of the Diamond Dealers Club and in other warrens high above 47th Street that the big trading is done -- the wholesale buying and selling that draws merchants to New York from all over the world. These multimillion-dollar deals are as invisible to the rest of the world as the high-finance operations on Wall Street.

These wholesalers -- bearded Hasidic Jews dressed in black; Arabs; Italians; Indians; Japanese -- display their diamonds on long green tables under fluorescent lights on one floor of the club. Screened before they enter the trading area through remotecontrol doors, members take their stones to electronic scales to obtain official weights and then trade briskly until the club closes at 6 p.m.

The club keeps no diamonds on its premises, leaving every dealer responsible to store his diamonds in one of the myriad vaults available for rent along 47th Street.

The Diamond Dealers Club is one of 16 "bourses" or trading clubs around the world that the tight network in which virtually all the reputable wholesale deals are made. There are currently 1,700 members in the club. The going rate for membership is $5,000, although a long waiting list renders the price academic.

Members of the other bourses wheel and deal at the New York club. On any given day, they may come from the Beurs voor Diamanthandel (the bourse in Antwerp, which has been the world's diamond capital for 600 years) or from the Israel diamond exchange in Tel Aviv, the home of a thriving diamond industry that has sprung up with the Israeli government's help in the last 25 years.

Or they may come from Bombay, the fourth world diamond center. Bombay's rise in diamonds is due largely to the extraordinarily cheap labor abailable in India to cut and polish the stones.

But it is in London, where the "syndicate" is centered, that the shots are called. Officially named the DeBeers Consolidated Mines Ltd. by the legendary Cecil Rhodes, founder of the modern diamond industry, the syndicate mines and controls upward of 85 percent of the world's supply and, in doing so, controls the price. It sells set numbers of stones 10 times a year to a select group of dealers and manufacturers. Although it is a classic monopoly, the syndicate is generally regarded within the industry as a more effective and responsible regulator than any government could be.

The history of diamonds and the history of Jews are strongly intertwined, and the events that link them date back 600 years. After centuries under Moslem rule, Jews in Spain and Portugal again became the target of Christian massacres in the 1300s. In 1492, they were banished by a royal Spanish edict. Expulsion from Portugal came later. Vast numbers fled to came later. Vast numbers fled to North Africa, Turkey and Italy but many turned north, to the more tolerant societies of Belgium and Holland.

Antwerp blossomed in the early 1500s when most of the world's diamonds still came from India.

Why did Jews find security in diamonds? Said one merchant who operates one of the largest centers on the street:

"Gold and silver were something you could escape with. But diamonds, they were the easiest to run with. Not bulky, easy to hide. How many escaped by giving someone a diamond?" He shook his head with a touch of amazement and sadness.

"So what does a Jew do? He sells everything for as much as he can get, even at a sacrifice. And he says, 'Give me diamonds.' Then, if he gets out, he either sells them and goes into another business or he sells them and stays... But always it's the smartest who escape. Always."

Before World War II, the New York diamond district was around Canal Street at the lower end of Manhattan. After the war diamond dealers moved to the 47th Street area for a safer neighborhood and better access to more customers. While some retail diamond dealers still operate in the Canal Street area, the members of the Diamond Dealers Club look down their noses at them.

"It's a joke down there now," says one silver-haired member with a 14-carat diamond in an envelope in his pocket. "It's dangerous. The people aren't reliable down there."

Satya Gupta, the 27-year-old Indian dealer who vanished March 10 with about $300,000 in diamonds and other gems, worked in the Canal Street area, club members are quick to point out. And, they emphasize, he was not a club member.

Gupta's body was found in Pennsylvania a short time later -- without the jewels.

Still, to carry as much as half a million dollars on one's person, as did Martin Paretsky before he disappeared on March 8, is risky anywhere.

A member of the Diamond Dealers Club, Paretsky was on his way to show his diamonds to an "out of town customer" at the New York Hilton when he disappeared.

"They're all nuts to carry diamonds around like that. It's crazy," says Bruce Kamm. "I'm frankly surprised it doesn't happen more often."

New York police detectives tend to agree with him. "I'm amazed that the count is so low," says one detective. "They do it all the time, and they meet the wrong people on the street. Someone fingers them when they walk out of a building, they get pushed into a car, and that's it."

William Goldberg, president of the Diamond Dealers Club, talks of augmented security on the street, to be paid for cooperatively by those who do business there. This idea, he admits, has come up before without results.

There are uniformed and plainclothes officers on the block, as well as security men hired by the larger firms and millions of dollars worth of electronic security software. But to cover potential losses, almost everyone insures his goods.

There's only one name for this kind of insurance -- Lloyds of London. Premiums routinely run into tens of thousands of dollars annually, and Lloyds is the only firm in the world with the expertise and experience to cover such risks. Yet some men, believe it or not, carry no insurance.

The well-respected memver of the Diamond Dealers Club with the 14-carat diamond in his pocket, a third-generation dealer who gained his acumen as a boy in Antwerp, has never insured any of his stones.

"It would cost me about $15,000 a year," he says. "I've been doing business for 40 years. You figure it out."

The divisions within the district are defined, among other ways, by age. Young dealers such as Bruce Kamm simply won't take chances with their lives and goods the way their father's generation does. They want to get away from the "schlock" image of the street, to use more sophisticated marketing techniques -- to come into the 20th century.

"You're considered an adolescent in here till you're 50," says Abe Shainberg, assistant executive director of the Diamond Dealers Club. "You're considered a mature man between 60 and 80."

Techniques may change. Security may improve. Innovations may enter the diamond market. Laser beams are beginning to replace the sawyers and cutters in the carving of an uncut piece. The old "cockers" (or small-timers) in their booths may die out, and the Hasidic Jews -- long the symbol of the 47th Street world -- eventually may decline.

But the guts of the trade -- greed -- is timeless. Dealers on 47th Street sell diamonds to make money, and the rest of the world wants to wear them. Forty Seventh Street need never compete with Fifth Avenue. A diamond is a tremendous ego massage. This indisputable fact is more fundamental than the standard industry line about its value as a hedge against inflation, which it is.

And then there's the game of buying and selling stones. It's like trading marbles.

Now that's just plain fun.