I'm actually siding with the idea of special gems not offering the hilariously large advantages that they do if stacked at the moment (see paracelsus gem, syrillax eye gem) because it widens the gap between the super wealthy and the middle class (plus the new players) even more.

There's no way to reach the best end game/twink setups that include multiple paragems and syrillax eyes for a new player, for example. That automatically means he/she cannot compete in neither pve timed runs nor in pvp without dishing out a ton of real cash (which also requires getting lucky! -- AL being the only game you can throw in 2k usd and walk out without the best of everything) and that's a huge turn off to anyone who just picks up the game. Not saying the more seasoned players should not have an advantage for sticking around longer but at the situation we're in, there's too large of an edge.

So no, if this gem is properly buffed (eg. made armor to scale too) and made as rare as vials (which are not all too common, just useless since there are no fossils to be crafted) it should offer a significant advantage that is maximized at 2-3 supergems tops.

Proposal:
First two supergems offer 2.4% and 2.6% armor and that's it, third and so on offer 0.25%. With this type of gems both old and new players can opt for more diverse gem setups without an unreasonable amount of gold needed.