By MICHAEL M. GRYNBAUM

Twenty-four meters below the sidewalks of Lower Manhattan lie half a million bars of gold, the most valuable stockpile of bullion in the world.
Recently, the market value of that gold, held in the vault of the Federal Reserve Bank of New York, approached $242 billion.
And several kilometers south, Steve Martinez, who owns a slightly smaller hoard of gold, stared at his television in disbelief.
“I’m sitting here, I have that TV on all day, and I’m watching the reports of gold,’’ said Mr. Martinez, who runs a company that supplies gold leaf to highend restaurants, churches and Las Vegas casinos out of his home on Staten Island.
“It’s $1,000 an ounce!’’ It was a historic day for a historic metal.
Gold - pride of kings, tempter of men and one of the world’s earliest currencies - has gone through an immense price run-up in recent months.
And on March 13, the treasure of millennia finally ticked past the millennium mark, at $1,000 a troy Gold has always been a refuge in troubled times.
In early 1815, when Napoleon escaped from Elba to return to France and war seemed imminent, the price of gold in London rose more than 20 percent;it fell back that June after he was beaten at Waterloo.
“Gold has longevity.
It doesn’t go bad,’’ said Bart Melek, global commodities strategist at BMO Capital Markets in Toronto.
“It’s hard to replicate.
’’ Last year, as financial markets began to quake from the subprime mortgage turmoil, some began watching gold as a recession gauge.
“I think if everything hit the fan, this would be something to own,’’ the economist Peter L. Bernstein, an expert on gold, said in an interview last fall.
And as the credit crisis became more severe ? and costly oil and food edged up inflation ? the run-up in gold prices accelerated.
“Gold is a good barometer of financial and economic events,’’ said James Steel, chief commodities analyst at HSBC.
“The credit crisis has triggered a lot of safe-haven buying in commodities in general, but particularly in gold.
’’ With the dollar falling to record lows and the Federal Reserve sharply dropping interest rates, gold has become an even more attractive investment.
The increased demand comes as the amount of gold being mined in South Africa, the world’s largest producer of precious metals, has declined.
The South African government recently said that widespread electrical failures had reduced the supply of precious metals.
Gold output plummeted 17 percent from a year earlier and the country’s overall mining output dropped by the most in at least 10 years.
In Rockefeller Center in Midtown Manhattan, Robert B. Raiber, a dentist, was warning patients that the price of installing a gold crown was about to go up.
“Patients will see a 10 or 20 percent increase on what it may cost to do a gold in- lay or a crown,’’ said Dr. Raiber, who sits on the board of the New York State Dental Association.
In Manhattan, Dr. Raiber said, gold crowns already cost up to $2,000.
The amount of gold in a complete crown - three pennyweights, or less than a fifth of an ounce - would now fetch $149.
81 on the open market, up from $103 a year ago.
The high prices are forcing some patients to consider other options, like crowns made of porcelain or acrylic.
“Gold is the best restorative material known to dentistry, bar none,’’ Dr. Raiber said.
But, he added, “the combination of a recession and the increase in cost for dental work may cause people to hold back.
’’ Back on Staten Island, Mr. Martinez said that the cost of importing the gold for his business, the Gold Leaf Company, was on the rise.
“I’ve had to raise the prices,’’ he said.
Two grams of decorative gold powder, which Mr. Martinez recommends storing in a “small empty pepper shaker’’ for ease of use, now costs $120, up from $95 in June.
As the markets buzzed over $1,000- an-ounce gold, Mr. Martinez was hardly glowing.
“This whole thing has been nothing but a headache,’’ he said.