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

Detail 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 high resolution detail of the difference between ISO and COS brightness over an encompassing range of conventional design angles. 2501 data points are graphed for the difference between ISO and COS brightness corresponding to angles from 30° to 50° pavilion mains in .5° increments and 20° to 50° 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