Sotheby's will offer a dazzling 8.03-carat "pigeon's blood" Burmese ruby ring as one of the highlights in its forthcoming Hong Kong Jewels and Jadeite Autumn Sale 2013.
The sale will take place on October 7, with the Premier Blue diamond - an expected record-breaker - set to steal the show at $19m. The ruby ring, an extremely rare find, will sell for between $3.5m and $4.2m.
Rubies are some of the world's rarest gemstones, composed of corundum with traces of chromium - one of the scarcest elements on Earth, which gives the stones their fiery red glow.
Burmese diamonds from the legendary mine in Mogok Valley, such as the example offered, are becoming increasingly sought after and, according to Sotheby's, have seen impressive prices at auction recently.
The ring itself was designed by one of the most celebrated Asian jewellery designers Cindy Chao, who has created a diamond set ribbon that will serve as a suitably magnificent mount for the stone.
Further highlights include the Cartier Red Peacock Brooch, which comes to auction from a royal private collection. Valued at $400,000-500,000, the piece is unique, created as a special commission from Cartier.
The centrepiece of the brooch is a cushion-shaped ruby, weighing an impressive 48.57 carats, which is complemented by the peacock's plumage. It is comprised of brilliant cut, marquise and pear-shaped rubies and diamonds weighing a total of 28 carats.
The piece is similar to Cartier's diamond and onyx panther bracelet, which sold for £4.5m from the collection of Wallis Simpson in 2011 to become both the most valuable Cartier item and most valuable necklace at auction.
The sale follows two high-profile jewellery robberies in Cannes, which inspired our Top 10 jewellery and diamond heists list. Sign up to our free weekly newsletter for more of the latest from the auction world.