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.

* A 1.71-carat heart-shaped fancy red diamond with SI2 clarity surrounded by white diamonds and mounted on an 18k white and pink gold pendant for a necklace. Its estimate is $2.5 million - $3.5 ...