A Graphical Presentation of Brightness in the Standard Round Brilliant
| Article | ISO Overview | COS Overview | Difference Overview | ISO Detail | COS Detail | Difference Detail |

Overview of the Difference Between ISO and COS Brightness
as a Function of Pavilion/Crown Angles and Refractive Index for the SRB
This graph presents a relatively low resolution overview of the difference between ISO and COS brightness over a very wide range of possible design angles. 375 data points are graphed for the difference between ISO and COS 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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Bob Keller