Last week, we got an emerald cut in for a client. Although I’m not a huge fan of emerald cuts, as they’re not as bright as brilliant cuts, this one looked nice due to it’s excellent symmetry and seemingly good light return.
Examining it under the Ideal-Scope, it looked pretty good:
However, under the AGS ASET, it was a different story:
So, what does this mean?
Well firstly, the Ideal-Scope shows very little light leakage, which is a good thing. However, upon further examination with an AGS ASET, it is revealed that most of the light is being reflected at a less that ideal angle.
In order to understand this, it is important to understand how the ASET works. Unlike the Ideal-Scope, the ASET uses a tri-colour filter that gives light being reflected at different angles a different colour. Green represents the light being reflected in the direction of the walls (assuming you’re inside) or your arms, and therefore less intense Red represents the light being reflected at the best angles and therefore, when viewing the stone perpendicular to your head, is the most intense. Blue represents the light being obstructed by your head, however, if you remove the head obstruction, it will produce the most intense light.
Back to the original example, you can see that most of the light is being reflected back towards the wall and the viewer’s arms. This is a perfect example of why “For buying fancy cut stones, we recommend initial face up selection with an ideal-scope – followed by final selection using your ASET scope.”
Anyone want to guess the AGS light performance grade???