Program aims to educate young consumers about mined stones’ positive qualities.
Ring featuring 20.19-carat stone sells for $13.2 million.
November sale also features jewelry from Fred, Bulgari, and other top houses.
Ring featuring the 1.21-carat, VVS2 stone fetches $275,000.
This was highest total for the company’s London branch since 2010.
25-carat yellow-diamond ring by Bulgari achieves $2.8 million.
Ring featuring pear-shaped, 8.38-carat stone is top item.
Kashmir sapphire weighing 7.58 carats fetches $1 million — more than double its upper estimate.
Cushion-cut stone carries high estimate of nearly $435,000.
Christie’s garners $202.2 million from three-part auction.
Ring from Heidi Horten collection garners $14.6 million.