Guild Wars 2

So I have a ornate ruby jewel inside of it, and I want to put a exquisite ruby jewel inside of it but it wont let me.

Is this because the backpack is level 78 and the jewel is level 80?

What are the rules about putting something in an upgrade slot/also infusion slot and deciding to put something else in it later?

Yes, the reason you can’t put an Exquisite jewel in is because its a level 78 item. Exquisite jewels can only be put in level 80 gear.

One of the crafted back items like the Elegent Jeweler’s Pack and a level 65 jewel is better than a normal Exotic backpiece with an Exquisite Jewel anyway, though. So its not really a bad thing. Just a bit confusing, perhaps.

There are no rules on putting an upgrade in and changing later. You can always slot a new upgrade into an item, it’ll just delete the old one.