From: G&G Brief  6 October 2009

Intensely colored pink and red diamonds are very rare in nature. As a result, various methods have been developed to induce or enhance these colors in natural diamonds. GIA’s New York lab recently examined a large (8.44 ct) Fancy Vivid orangy pink pear shape submitted for grading that was found to have had its color introduced by a relatively new treatment. This diamond showed an even color distribution and was internally clean. Spectroscopic analysis revealed a very low concentration of aggregated B-form nitrogen and trace amounts of isolated nitrogen. Strong absorptions from NV centers at 575.0 and 637.0 nm were the main cause of the treated-pink color. Also observed in the UV-Vis-NIR spectra were moderate absorptions from the ND1, H3, H4, 594, and GR1 defects. All the observations strongly indicated that the treatment process involved HPHT annealing and subsequent irradiation and annealing at relatively low temperatures.

Read More