Astral Gem/Gem of the Stargazer - Need more mana? This gem holds energy like a vast section of cosmos. At higher rarities, pop it into a pickaxe to get source gems out of lazuli without the wait.
Gem of Terror/Shard of Terror - Get more damage out of your spells with a fragment of fear itself!
Endergrade Gem/Endergrade Pearl - This gem is only found at high rarities in a distant otherworldly plane. This embryo imbues objects with strange, rare effects.