A 6.89-carat diamond with a color grade of Fancy Vivid Purplish-Pink is one of the star stones set to be auctioned at Christie's New York Jewels sale of diamond and colored gemstone jewelry on Tuesday.

The pink diamond is set in a ring, surrounded by pave-set pink diamonds, and is expected to sell for over $6 million. November saw two spectacular sales of pink colored diamonds, with London jeweler Lawrence Graff buying a 24.72-carat Fancy Intense Pink diamond for nearly $46 million. Two weeks later, an anonymous buyer secured a 14.23-carat rectangular-cut diamond known as the Perfect Pink for $23 million - considerably more than its estimate price of $14-19 million – at a Hong Kong auction.

Other star pieces of the Christie's sale include a 22.79-carat cushion-cut D-color diamond ring, estimated at $2-3 million; a 10.91-carat pear-shaped diamond ring color graded Fancy Intense Pinkish Orange, also estimated at $2-3 million; and a 10.71-carat Flawless pearl-shaped diamond ring, estimated at $1.2-1.5 million.

A 12.15-carat oval-cut Burmese Ruby and Diamond Ring is expected to fetch anywhere from $800,000 to $1.2 million, while a 37.57-carat cushion-cut Kashmir Sapphire and Diamond Ring is estimated at $450,000-$500,000.