Neither getting bonus Gem Drops or Doubled Gem Stat Bonuses.
Let me surmise…
- You have the Broken Crown on your follower, emanating its effect
- Your hero has a helm with a new soul shard in it
The Broken Crown’s effect is that it will drop extra gems of the same colour as the one in the helm (when emanating, this refers to the gem in the hero’s helm, not the follower’s). It specifically states that it does not work for legendary gems. Now, shards are neither legendary gems or coloured gems, i.e. the reason you’re not getting any extra gems dropped is that there’s no coloured gem in your hero’s helm for it to duplicate.
The same is true of Leoric’s Crown, as Meteorblade stated, if you have a Legendary Soul Shard inserted in it. The Soul Shard Properties WILL NOT be doubled.
And if your Follower has Leoric’s Crown equipped, only regular Gem Properties are doubled… for your Follower. Like a Diamond for Cooldown Reduction or an Amethyst for Vitality. Leoric’s Crown’s Power DOES NOT Emanate.