Who is this gentleman and why is he smiling? Well, Brett Stettner, a diamond dealer and head of a diamond investment fund, stunned the auction world last week when – within a 24-hour period – he purchased two highly prized colored diamonds for a combined $18 million. The successful bids were made at back-to-back events at New York's Sotheby's and Christie's. On April 17 at Christie's, Stettner placed the winning bid of $15.7 million for The Clark Pink, a 9-carat cushion-cut purplish pink diamond from the estate of the reclusive heiress Huguette Clark. The bid shattered the pre-auction estimate of $6 to $8 million and set a record for the highest price ever paid for a pink diamond sold at auction in the U.S., according to JCK Magazine. Only one day later, Stettner secured a 3.54-carat marquise-shaped fancy blue diamond ring for $2.4 million at Sotheby's. The piece sold for nearly five times the pre-auction high estimate of $500,000. JCK Magazine reported that the purchase price of $687,712 per carat was a world record per-carat price for a fancy blue diamond, topping the 20.17-carat fancy blue diamond ring that sold for $490,952 per carat at Sotheby’s in October 1994.