The three fully charged gems are shown with a quantity of 2, total weight of 4.
Dropping one of the fully charged gems changes it to the correct values of a quantity of 2, total weight of 2. Picking it back up changed those to 3 and 3, so it corrected the glitch.
I'm assuming the weirdness started when I used some charges a little while ago. 'Total Weight' on the inventory tab seems to be correct. The 'Weapon' tab appears to show the gems correctly.
I want to say this is the second time I'm seeing this. Not sure if it was the same alt.