Rough Green Diamond

By Riccardo Befi

Recently, the AGTA GTC had the opportunity to examine some green diamond rough ranging from 0.50 to 0.90 ct. (Figure 1). One of the first indications for natural color we were looking for when first examined with a microscope was the presence of brown or green radiation stains (Figure 2).
    These stains are indications of radiation damage to the diamond through radioactive rock or soil in the diamond deposit. Most of those pieces of rough had several green spots, sometimes grouped in one area or distributed randomly throughout the surface.
    When cut, these pieces of rough will probably no longer be green, since the vast majority of natural–color green diamonds are only green on the surface of the rough, with the color produced by surface stains and coatings.
    Maybe the cutter, with some luck, will be skilled enough to get a nice fancy-green stone from the rough and be able to leave some of those green "stains" somewhere (typically on the girdle) as proof of natural color.





 



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