If I don't have the HCA calculator with me, what CUT guidelines should I use?

You can print this out and take with you, these are some numbers some of us use in order to find a well cut round diamond.

depth - 60 - 62% - although my personal preference is to allow up to 62.4%
table - 54- 57%
crown angle - 34- 35 degrees
pavilion angle - 40.6- 41 degrees
girdle - avoid extremes, look for thin to slightly thick, thin to medium etc
polish and symmetry - very good and above

note - with crown and pavilion angles at the shallower ends ( CA 34- PA 40.6) and steeper ( CA 35- PA 41) check to make sure these angles complement in that particular diamond - eyeballs, Idealscope, trusted vendor input - check as appropriate!

As the above implies, configurations depend on each other.  A little give here can still work with a little take there.

From expert John Pollard.

With that said, here's a "Cliff's Notes" for staying near Tolkowsky/ideal angles with GIA reports (their numbers are rounded):  A crown angle of 34.0, 34.5 or 35.0 is usually safe with a 40.8 pavilion angle.  If pavilion angle = 40.6 lean toward a 34.5-35.0 crown.  If pavilion angle = 41 lean toward a 34.0-34.5 crown.

 GIA "EX" in cut is great at its heart, but it ranges a bit wider than some people prefer, particularly in deep combinations (pavilion > 41 with crown > 35).

Nothing is more sacred as the bond between horse and rider...no other creature can ever become so emotionally close to a human as a horse. When a horse dies, the memory lives on because an enormous part of his owner's heart, soul, very existence dies also...but that can never be laid to rest, it is not meant to be...
- Stephanie M Thorn

"I like smiling. Smiling's my favorite!" Will Ferrell ~ Elf