Named the Leibish Pink Promise and graded by the GIA, the cushion-shaped diamond was produced from a 4.96-carat rough stone, the firm said in a media statement.

The purplish pink hue is one of the rarest colors available with an extremely high market demand, the company said. "Given the impressive price performance of both the important diamonds sold in the auction houses as well as smaller diamonds traded among the general public, colored diamonds are becoming much sought after investment options," says Leibish & Co. CEO Yossi Polnauer.

The rough diamond was uncovered at Kao in South Africa, and Leibish & Co. bought the rough stone at the Kao tender in Antwerp in November 2012.

"It requires great expertise to determine the right shape of an important stone," says Shmulik Polnauer, the firm's chief diamond buyer. "By cutting a heart shape, we had fair chance to finish with a 1.80-carat, with VS2 clarity. We did not want to compromise on the color saturation and wanted to keep the stone over 2 carats. This diamond is of the finest bubble gum color, with some fresh reddish flashes in the face up. It compares well with a vivid purplish pink from Argyle in its body color and luster," he explains.

The majority of pink diamonds are mined at the Rio Tinto-owned Argyle diamond mine in Western Australia.

 'We spent over four months assessing and then polishing this 4.96-carat rough pink diamond. We saw an enormous amount of potential and wanted to ensure the world appreciates the outcome. In addition to buyers looking for truly unique pieces, we expect many investors to show interest in this diamond due to its rarity and ability to appreciate in value over time," he adds.