I believe this bug has existed since 1.32 -- not sure about before that.
If you visit a merchant, the gem bag shows up as an unidentified item. You can pay 100 to identify it, whereupon it disappears from the trade screen. Identifying it has no further effect.
Actually I believe strongly that the gem bag should show its attributes (based on the gems in it), just as items with charms should show the attributes conveyed by the charms, as in Divine Divinity. And unused gems and charms should show their effects.
Another small item bug: the ring called "bone spear" which has weapon stats rather than ring stats is still there. And it seems to be being over-generated -- I just found three of them within a few feet of each other in a battlefield dungeon!
