Geneva is set to host the season's most important jewellery and watch auctions, with buyers expected to part with up to SFr150 million ($133 million).
The biggest cut diamond ever sold at auction will be the highlight of the coming week, with an estimated market value of up to SFr20 million.
The unnamed gem, proposed by Sotheby's, is considered by experts to be flawless and has been given the highest rating for a white diamond.
"This stone must be among the most beautiful diamonds I have seen in a 32-year career," said David Bennett, director of international jewellery for Sotheby's Europe.
Another diamond, blue and pear-shaped, could be worth another SFr4 million. Sotheby's will be putting forward 387 lots of jewellery on Wednesday, potentially worth a total of SFr50 million.
Also on sale are 158 watches, with an estimated value of up to SFr7 million, including a piece by Geneva watchmaker Patek Philippe, an automatic model valued at SFr500,000.
The auction house will be hoping that the sale will be more successful than the one that saw a Van Gogh landscape fail to find a purchaser this week in New York. That sale brought in $270 million, instead of the anticipated $355 million.
This lacklustre performance saw Sotheby's shares drop 28 per cent on Thursday.
Sales in Geneva begin on Sunday with watch specialist Antiquorum proposing more than 300 timepieces worth about SFr10 million.
A number of rare watches are included in the auction, including a Patek Philippe model with 16 complications and valued at SFr800,000.
Sotheby's main rival, Christie's, will also be tempting buyers, selling off 12,000 bottles of wine over two days, worth up to SFr5 million. Included in the sale are 3,000 bottles that once belonged to fallen Swiss financier Dieter Behring.
This wine is being sold at the request of the Federal Prosecutor's Office. Behring, who is under investigation, is alleged to have swindled dozens of investors.
The collapse of his investment system left a shortfall of hundreds of millions of francs.
Christie's will also be selling off watches and jewellery, including a red diamond with an estimation of SFr1.5 million. The auction house is hoping to achieve total sales of SFr80 million.
Philipps de Pury & Company will also put 180 lots of jewellery up for sale on November 13 in Geneva, looking for an estimated SFr10 million.
swissinfo with agencies
Geneva has been a major centre for auctions since 1968, especially for jewellery and watches.
Last spring, sales of watches, jewellery and fine wines were worth more than SFr140 million.
Sotheby's is one of the world's two biggest auction houses, the other being Christie's.
Sotheby's, founded in 1774 by a bookseller, is a publicly traded firm, while its rival remains in private hands.
Christie's first auction was held in 1766.
Annual turnover at both companies is worth more than $2 billion.
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