Guild Wars 2

It’s a back item but unlike my other back item I can’t put a gem/jewel into it is this intentional?

it’s because it has no level requirement. to place one of the better jewels on an item the item hase to have a level requirement of XX+ depending on which jewel you use. the best jewel require an 80+ level requirement on the items if I’m not wrong.

If you have any fine transmutation stones you could transmute it over to a better back slot.