With one out of every three diamonds sold in the U.S. being a classic round brilliant diamond, this cut is far and away the most popular.
Scarlett Johansson and singer Fergie both sport classic rounds.
The princess diamond was created in 1980 but has catapulted into massive popularity, making it the second-most popular diamond cut in the U.S. Diamond analyst Kenneth Gassman estimates that princess cut diamonds make up approximately 13% to 20% of diamond sales.
Freddie Prinze Jr. proposed to Sarah Michelle Gellar with a princess cut.
The third-most popular cut has long clear "step cuts," which emphasize the diamond's clarity and gives it a more subtle appearance than the "brilliant" cuts of most diamonds.
Nick Cannon proposed to Mariah Carey with a reported $2.5 million emerald-cut diamond.
The pear shape, the fifth-most popular diamond, is also called a "tear drop" for its single point and rounded end.
The most famous pear-shaped diamond has to be the 69-carat pear-shaped diamond given to Elizabeth Taylor by her fifth and sixth husband Richard Burton. Taylor wore the Taylor-Burton diamond in a necklace.
The Asscher cut has been around for a century but soared in popularity, especially in Hollywood, after being featured in an episode of Sex and the City in which nice-guy Aidan proposed to protagonist Carrie Bradshaw.
Kate Hudson and Elizabeth Hurley were both given Asscher cuts by their soon-to-be husbands.
Source: Kenneth Gassman, The Diamond Source of Virginia, Blue Nile.
source : http://forbeslife.nl/2009/04/17/engagement-weddings-diamonds-forbes-woman-style-retail_slide.html?partner=contextstory