Cuboid diamond with a square heart
The photomicrograph below shows a yellow cuboid diamond crystal (0.13 ct – type IaA>Ib>>B) with an unusual internal structure that possesses three whitish cuboid concentric layers as well as a strong inhomogeneous yellow color repartition, rarely encountered in isotropic materials.
This sample is inert under both SW- and LW UV lights, with no phosphorescence [1]Massi L. (2005) Studies of defects in brown and hydrogen-rich diamonds, PhD thesis, University of Nantes – France, 372 pages (PDF).
Cub-oid (cuboid term is made of “cub-“ from cubus, the cube and “-oid” from eîdos, the shape) diamonds are diamonds that show a kind of cube-like shape with wavy faces and rounded edges, features that set them apart from the regular cube that possesses planar faces and sharp edges [2]Rondeau B. (2007) Proper Terminology for Diamond Growth, Gems & Gemology, Vol. 43, No. 2, pp. 96-97.
For lovers of scientific data, this diamond is hydrogen- and nitrogen-rich with a low aggregation state of nitrogen defects (single substitutional nitrogen impurity – type Ib character – causing the yellow coloration) [1]Massi L. (2005) Studies of defects in brown and hydrogen-rich diamonds, PhD thesis, University of Nantes – France, 372 pages.
To go further:
(literature the reader might be interested to read to get more technical information on the topic covered in this blog post)
- Ragozin A., Zedgenizov D., Kuper K., Kalinina V. and Zemnukhov A. (2017) The Internal Structure of Yellow Cuboid Diamonds from Alluvial Placers of the Northeastern Siberian Platform, Special issue of Crystals: « Diamond Crystals », 7(8), 238.
- Rondeau B., Fritsch E., Guiraud M., Chalain J-P. and Notari F (2004) Three historical ‘asteriated’ hydrogen-rich diamonds: growth history and sector-dependent impurity incorporation, Diamond & Related Materials vol. 13, pp. 1658– 1673.
- Zedgenizov D.A., Kalinina V.V., Reutsky V.N., Yuryeva O.P. and Rakhmanova M.I. (2016) Regular cuboid diamonds from placers on the northeastern Siberian platform, Lithos, 265, 125–137.
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