A 6.13-carat fancy intense green diamond set a new per-carat record when it sold at Christie’s on May 27 for a whopping $3.6 million, or $594,510 per carat. The square cushion cut diamond is the center of a rose gold halo style ring, accentuated by natural pink diamonds.
Next to red, green is the rarest of colors found in natural diamonds. For most colored diamonds, the color comes from trace amounts of mineral impurities or extreme pressure conditions while the diamond was forming. The tight chemical structure makes it very difficult for any impurities to enter, which is why colored diamonds are exceedingly rare. Small amounts of boron in the crystal lattice structure of a diamond, for example, will impart a blue hue; same goes with nitrogen for yellow, and hydrogen for violet. What gives a diamond a green hue however, is the presence of natural radiation over millions of years. Because the radiation exposure is an external force rather than internal force (such as mineral impurities and lattice defects), it acts on the surface only. As a result, green diamonds are not green all the way through; the color is concentrated on the outer layers and tends to be weakly saturated. That is why a fancy intense green diamond, especially one of a size like this one, is almost a once-in-a-lifetime find.
This spectacular diamond joins the ranks of other recently sold, record-breaking gems at Christie’s. At their Geneva auction just last month, there were three record-breakers alone. They include ‘The Blue’, a fancy vivid blue pear shaped diamond weighing over 13 carats, a 76.5 carat light pink square-cut diamond that sold for $10.2 million, and the ‘Ocean Dream’ – a 5.5 carat, vivid blue-green diamond that went for $8.8million.