Re: HCA and different crown angles

[Maxine]

RE: HCA - Just curious about crown angles.....Just out of curiosity, I have been playing w/ the HCA and plugging in different #''s....some of diamonds listed by vendors or on various educational websites....("examples").....A lot of diamonds with low HCA scores come out, Ex,Ex,EX,VG......
This occurs even when the crown angles are less than 34 (which supposedly is true of my own diamond)......I thought lower crown angles exhibited les "fire." So why do these stones come up EX for fire?

 

[Garry H (Cut Nut)]

When diamonds get a little shallow they can show more fire because they loose a little brightness.
Brightness stops us seeing the fire.

 

[KBerly]

Garry,

is a 33.3% crown too shallow?? how about these specs for an RB..

table 57.9%
depth 60%
crown 33.3
pav 40.8
culet 0.7%
girdle medium 1.5

measures 7.87x7.90x4.74
scores a 0.8 on the HCA X/X/X/X

 

[Garry H (Cut Nut)]

This is a chart for about 555 table i think - and 33 degrees (not %) makes it - but you can see that the AGS range goes nearly to 30 degrees

 

[KBerly]

oh yes, 33.3 degrees...sorry. thanks garry