Starry Night in Diamond
In astronomy, a star cloud is defined as a group of many stars. A diamond recently submitted to GIA’s Surat lab contained cloud inclusions resembling a starry night (figure 1). This diamond was a 0.53 ct D-color natural round brilliant with SI2 clarity. Fourier-transform infrared absorption spectroscopy indicated a type IaAB diamond with low nitrogen content of about 5 ppm. Each of the cloud inclusions had apparently randomly placed dendrites. The star field in this stone appeared comparable to a diamond described previously (Fall 2017 G&G Micro-World, p. 369); however, the individual clouds in that diamond resembled crosses of uniform orientation that corresponded with the cube face.
Photoluminescence (PL) mapping using 455, 532, and 633 nm excitations was used to determine whether optical features could be detected within the cloud inclusions, as that analysis method has proven useful with cloud features in other diamonds (Fall 2020 Lab Notes, pp. 416–419). However, the PL maps were inconclusive, as no distinctive features were detected within the star-shaped inclusions. In deep ultraviolet fluorescence imaging, they appeared to be contained within the same growth zone (figure 2).
The inclusion suite was an interesting collection of cloud formations and a delightful discovery in this unusual diamond.
