Two hearts, one blue, the other pink, will appear at Sotheby’s Hong Kong Magnificent Jewels auction as if they were always meant to be together. They will be sold separately during the July 10 sale at the Hong Kong Convention & Exhibition Centre. Combined, their high estimate is $18.5 million.

The first is a 5.04 carat fancy vivid blue heart modified brilliant-cut diamond. The gem has a VS2 clarity grade, according to its lab report. The heart-shaped gem is mounted on a platinum ring flanked by two pear-shaped diamonds. Its estimate is between $7.7 million and $9.7 million.

Its would-be partner is a 4.49-carat heart modified brilliant-cut, internally flawless, fancy vivid pink diamond. It’s mounted on an 18k white gold ring flanked by pear-shaped diamonds. Its estimate is between $7.5 million and $8.8 million.