I settled for something else and overcharged a Firebolt spell to form inside the gem, the resulting heat would crack the gem quickly and shatter it, rendering it useless. Next, I start on the password system, it's not hard to make something like this as it's just me filling in something the spell expects to be there, and if it's not then it activates a link to the firebolt spell, but I still have to get creative for a reason I'll touch on in a bit.