So you've no doubt noticed by now that there are three different gem shapes, and it may seem at first that there is no difference between them, but there happens to be a big difference.Each shape has a stat that only it is able to give you:
Square, being critical chance.
Triangle being critical damage.
Diamond being resistance.
Every stat except the ones above, are available to every shape. Gem shapes are good to look out for, for the simple reason that many mons have skills based on crit, such as light jellai. It is also a good indicator on which mons you will be able to gear with gems early, for example if a mon doesn't need crit, all diamonds is a good indicator that you will be able to gear that mon faster than the others, since golem b7, and golem b4 are both the easiest golems to get your foot into.
