(IDEX Online) - Tiffany & Co is to sell the most expensive piece of jewelry in its 183-year history - a necklace with an 80-carat diamond that is expected to fetch at least $10m.The New York-based jeweler, founded in 1837, declined to say what it paid for the gem but told the fashion Bible Women's Wear Daily (WWD) the necklace's price tag would be "within the eight-figure range".Tiffany recently acquired the D-color IF-clarity gem, which was mined in Botswana and cut in Israel.It will showcase the finished piece when it opens its new flagship store on 57th Street and Fifth Avenue, New York, in spring 2022.The design of the necklace is inspired by a piece Tiffany had made for the 1939 World's Fair - which featured a 200-carat aquamarine stone and 429 diamonds, priced at $28,000 ($524,000 in today's money).Pic courtesy Tiffany & Co