It is generally understood that pink colour in diamonds results from significant stress causing a change in the diamond’s crystal structure known as plastic deformation,” said Dr. Sally Eaton-Magaña, senior manager of diamond identification at GIA in Carlsbad, California. “The pink section likely was initially colourless and then plastically deformed, perhaps by a mountain-forming event millions of years ago, resulting in its pink colour, with the colourless section forming at a later time.
An article analyzing the bicolor diamond by Dr. Eaton-Magaña, Kgotlaetsho Baatshwana (senior analytics technician), and Norma-Jean Osi (analytics technician), both at GIA in Gaborone, Botswana, is available on GIA’s website with photos and a video. The article will be published in the next print issue of the Institute’s quarterly journal, Gems & Gemology.