A gem-feature that would improve the early game

I'm against just buying gems from the vendor. That's too little friction for my taste.
But much like passive points, we should get to change a gem for a gold fee.

Make it cost the same as respecing a point on the passive tree. This allows for more skill exploration, as you can test all level 5 gems when you get them. This also allows for easier build-rerolling and more room to transition between builds as you level.

Make it an NPC feature (disenchanting a gem would be too hard to communicate). Introduce it EARLY, as in prior to meeting the hooded one, otherwise it causes needless friction.