A spectacular pink diamond, the largest of its kind to ever appear at auction, goes under the hammer in Geneva on Tuesday, with an expected sale price of more than $23 million (21.4 million euros).
The precious jewel's anticipated sale by Christie's is part of a week of auctions that could see another coloured gemstone set a new world record.
That stone, a 12.03-carat blue diamond described by experts as flawless, is being sold by rival auction house Sotheby's on Wednesday, possibly fetching a record $55 million.
"Coloured diamonds...have seen sustained growth during the last few years. Partly because of their great rarity, but equally because of their beauty," said David Bennett, head of Sotheby's international jewellery division.
Christie's 16.08-carat pink diamond is the largest cushion-shaped stone classified in the elite "fancy vivid" category to come to auction.
Rahul Kadakia, the International Head of Jewellery at Christie's, told AFP that the stone dubbed "In the Pink" could end up selling for more than $30 million.
He noted that the record price per carat for a pink diamond was set in December 2009 by Christie's in Hong Kong, when a five-carat stone sold for more than $10 million.
If In the Pink, owned by an American family for the past 15 years, matches that mark, it could fetch more than $32 million he said.
The jewel, he added, has been priced "well below what it is actually worth."
Christie's said that only three pink stones classified by the Gemological Institute of America as "fancy" and weighing more than 10 carats have been up for sale in 250 years.
A pink diamond holds the current world record for sale at auction, set by Sotheby's in November 2010 in Geneva, when a 24.78 carat pink diamond sold for $46 million.
- Bond watch -
Geneva's auction season, which began at the weekend, has already seen a number of high-profile lots snatched up, albeit at prices that seem ordinary compared to the enormous values attached to this week's coloured stones.
A Rolex watch worn by Roger Moore in the James Bond film "Live and Let Die" sold at a Philipps auction on Sunday for 365,000 Swiss francs ($363,000).
The estimated price for the stainless steel watch, made in 1972, was between 150,00-250,00 Swiss francs.
In the film, the watch is used to create a magnetic field which deflects bullets fired at the MI6 agent.
At Wednesday's Sotheby's auction, two pieces owned by another ex-Bond star will go under the hammer.
Scottish actor Sean Connery is selling a 15.4-carat pink and orange diamond, which could fetch above $2 million and a ring boasting 5.18 carats of diamonds, with an estimated sale price of $250,000. afp, photo by ctvnews.ca