Known as L'Incomparable, the necklace created by luxury jeweler Mouawad features a yellow, internally flawless diamond of more than 407 carats suspended from a rose gold setting that is studded with 90 white diamonds weighing nearly 230 carats.
"Serious interest" has been expressed by a couple of potential buyers from Asia, said Jean Nasr, managing director of Mouawad in Singapore, declining to identify their nationalities.
"People who will get something like this are looking at it from a different perspective because this is definitely an investment piece," he told Reuters.
The necklace, whose centrepiece diamond was found by chance in a pile of mining rubble by a young girl in the Democratic Republic of Congo about 30 years ago, will be the flashiest item on offer at the Singapore JewelFest on October 11-20.
But there will be plenty of other glitz from American, European and Asian designers worth another $200 million or so.
Singapore, a tiny Southeast Asian nation with the world's highest concentration of millionaires, has positioned itself as a destination for the ultra-rich with a busy wealth management industry, luxury properties, top hotels, gourmet restaurants, high-end boutiques and two casinos.
While the city-state boasts a very low crime rate, security will be extremely tight with so much jewelery on display at a pavilion outside an upscale mall.
It seems unlikely there would be a robbery in Singapore like the daylight heist of about $136 million worth of jewelery on show at a hotel in the French Riviera resort of Cannes in July.
But Filippo Melchionni, in charge of guarding L'Incomparable and the rest of the jewellery on show, is taking no chances.
Security includes armed guards, plainclothes supervisors, cameras, motion detectors and bullet-proof display cases but the most critical time is when the pieces are shown to customers.
"This is the moment that the stones are under risk because they can be passed hand-by-hand, they can be exchanged," said Melchionni, chief operating officer for Asia-Pacific at the Ferrari Group, an Italian logistics company for luxury goods.
"Every night it is going back to our vault. We have an armored truck to move the stones."
L'Incomparable, completed in 2012 and certified as the priciest necklace in existence by Guinness World Records earlier this year, is an extravagant novelty.
But Asia, especially China, has become an important and resilient growth area for sellers of pricey jewellery, cars, boats, wine, artwork and other lavish items.
Australian miner Rio Tinto Ltd, which showed off its finest coloured diamonds in Hong Kong last month, believes the United States will remain its key market for diamonds but sees China growing fast.
Demand for diamonds in China, now the world's second-largest market after the United States, helped boost global sales at Tiffany & Co in the latest quarter, leading the U.S. jeweller to raise its annual profit forecast.
The show in Singapore, now in its 11th year, expects some Chinese buyers but many locals and visitors from Indonesia, Malaysia, Thailand, Vietnam, Cambodia and Russia will also be there, said Kean Ng, chairman of the Singapore JewelFest.
"You have the high-end customers but of course you have the browsers coming in and they usually end up buying something that's within their budget," he said.
