Heat-treated brown diamonds

Heat-treated brown diamonds:
The observation that brown color might related to the lattice imperfections has led to a technique to convert brown diamonds into more valued light-yellow or even colorless ones: the diamond is subjected to high pressures of 6-10 GPa and temperatures above 1600 °C that heals (anneals) those defects.The technique has been demonstrated in several research laboratories in Russia and US. In March 1999, Pegasus Overseas Ltd (POL) from Antwerp, Belgium, a subsidiary of Lazare Kaplan International, has started marketing of such diamonds which were processed by the General Electric (GE). Those diamonds have therefore received a name GE POL (or GEPOL) and were marketed in the US as Bellataire diamonds. The fact and the identity of the treatment process was considered so important that micrometer-sized letters "GEPOL" were inscribed with a laser on the girdles of every treated diamond.In 2004, however, the GE diamond section has been purchased by Littlejohn & Co. and renamed into Diamond innovations. Since 1999, several companies around the world have adopted the technique and use various brand names for the processed diamonds.