Question about HCA and girdle size

[Second City]

I know that the results produced by HCA are for diamonds that have a medium girdle. Does this include thin-medium and medium-slightly thick, or does the girdle have to be entirely medium? Also, how "symmetrical" does a diamond have to be to fall within the criteria established for using the HCA? Thanks.

 

[Garry H (Cut Nut)]

From the data you enter HCA calculates the girdle thickness - so it is taken into account - especially in spread.

Symmetry though is an unknown - that is one of the reasons I like slightly shallower stones because poor sym is rather critical when you get nearer steep deep proportion sets.