How are diamonds affected by shallower crown angles. Does this result in less fire? more light leakage?
Are crown angles just as important as pavillion angles?
5 degree crown angle = about 1 degree of pavilion angle variation - it is much less important.
say crown angle 34.5 minus 5= 29.5 then take an ideal 40.7 pavilion angle and ADD 1 degree to 41.7 and you will have a very nice diamond.
It will be obviously brighter - return about 5% more light, but have noticable less fire.
But the shallow crown angle can easily chip at the girdle - so you should have at least a slightly thick girdle.
You can do the same thing the other way by +3 crown and - .6 pavilion angle.
Lower girdle lengths should be very long for the latter