The rarity of a rectangular-cut D Flawless diamond over 40 carats is not to be underestimated. To obtain such a stone, it would have to start as a rough diamond in excess of 80 carats. To put this in proper context, the Gemological Institute of America estimates that annually there are no more than 600 diamond crystals that finish as polished stones of between one and two carats and that are D colour, Flawless clarity. This number dramatically decreases after ten carats. This is out of a total worldwide diamond production which is in excess of 100 million carats per year.
Diamond rough originates in a number of forms and colours and the primary goal of every diamond cutter is maximum yield. To cut a rectangular diamond of this size while retaining an elegant shaped with very good polish requires sacrificing a lot of weight and is indeed very rare.
The reason diamonds are graded D colour, Internally Flawless clarity is because they not only lack traces of nitrogen, which is present in well over 99 of all diamonds, but because they are also free of any type of clarity characteristics, which a vast majority of crystals possess.
The 44.86 carat diamond offered here is one amongst a very select group ever offered at auction. To emphasize the rarity of this particular rectangular-cut stone, the chart below lists all the rectangular-cut D, Internally Flawless diamonds, between 40 and 50 carats, sold at auction over the last 30 years, it is indeed a distinguished list, making it truly desirable for the diamond connoisseur!
A rectangular-cut diamond of 50.83 carats
Auction in Geneva - November 18, 1992 (lot 571) $3,131,955
A rectangular-cut diamond of 50.58 carats
Christie's Geneva - May 27, 1993 (lot 491)
A rectangular-cut diamond of 47.40 carats
Christie's Geneva - May 27, 1971 (lot 1029) $635,695
A rectangular-cut diamond of 46.05 carats
Christie's Geneva - November 19, 1974 (lot 593)