A Graphical Presentation of Brightness in the Standard Round Brilliant

This graph presents a relatively low resolution overview of the behavior of ISO brightness over a very wide range of possible design angles. 375 data points are graphed for ISO brightness corresponding to angles ranging from 15° to 75° pavilion mains in 2.5° increments and 10° to 80° crown mains in 5° increments. This data set was systematically calculated for eight different refractive indexes ranging from RI = 1.43 (fluorite) to RI = 2.61 (sphalerite). Use the "Cycle" buttons on this graph to observe the significant effect of varying the refractive index as a variable affecting brightness.

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