The table is about the best equipment to get to maximise the speed of learning knowledge.
The shamans gear is not specific, so any shaman can use any piece of equipment.
So its Sigurd's Hood no matter the shaman , except of course Inga is the best for learning.
The gems for every piece of equipment are acquired in the same ways.
I think you will find the special gems you might need are dropped occasionally by Ubers.
There are several limited posts in the data section, this section, to cover all aspects, and one that I think covers everything.
https://plarium.com/forum/en/vikings-war-of-clans/666_game-database/98278_index-navigation/