A rare 1999 platinum Rolex Daytona featuring a mother-of-pearl dial with diamond hour markers — one of only four known to exist.Courtesy of Sotheby’sA legendary timepiece is about to step into the spotlight.A 1999 platinum Rolex Daytona is heading to auction on Sunday at Sotheby’s Geneva, and could sell for up to $1.7 million.The watch is made from platinum, a material Rolex did not use on Daytona models until 2013. Its face is mother-of-pearl, set with 10 diamonds. Unlike nearly every other Rolex on the market, it was not part of a standard collection. It was privately commissioned, custom-made for a client — something almost unheard of for Rolex.”It’s very unusual to come across a commission,” said Pedro Reiser, senior watch specialist at Sotheby’s. “There are other brands which might be more flexible and do these kinds of exercises, maybe on a regular basis — but not in the space of Rolex pieces where you barely can come across any commission whatsoever.”Only four of these watches are known to exist, made for the same family, each with a different dial. The watch heading to the auction block is the last one to be sold. The others have already gone for massive prices, topping $3 million.There is big hype around this small work of metal. It is believed to have been created under the leadership of Patrick Heiniger, Rolex’s CEO from 1992 to 2008. He ran the company during a time of major growth and secrecy and helped turn Rolex from a respected watch brand into a global luxury icon.Get Inside Wealth directly to your inboxThe Inside Wealth newsletter by Robert Frank is your weekly guide to high-net-worth investors and the industries that serve them.Subscribe here to get access today. While rumors have swirled that Heiniger personally commissioned or wore a similar platinum Daytona, Reiser cautions that there is no confirmed link to this watch.”That’s more of a rumor,” Reiser said. “Personally, I’ve never seen him with this piece, but I know that he used to love platinum watches — mainly Day-Date …