Iridescent Inclusion in Brown Diamond
This iridescent ferropericlase crystal with a stress halo measuring approximately 0.7 mm was trapped inside a light brown diamond. Photomicrograph by Kyaw Soe Moe; field of view 1.58 mm.
The iridescent crystal inclusion in the 1.07 ct light brown type IIa diamond in the figure above was identified by Raman spectroscopy as ferropericlase. Ferropericlase, (Mg,Fe)O, can originate from either shallow (lithospheric) or deep (sublithospheric) depths within the earth. A stress halo was developed around the crystal by temperature and pressure changes during the ascent to the earth’s surface. The colorful iridescence may have been caused by light interference at a thin film trapped between the inclusion and the host diamond. It is rare to see ferropericlase as an inclusion in diamond, especially such a large crystal.
