What generates gems?

[TheWetFish]

What generates gems?
Lots of sites generate gems, they are fairly well documented.

Some items produce gems. They can be found as a special effect in the list of items in the manual.

Random events can sometimes have a significant effect on gem income. Exact stats and mechanics unknown.

Some Pretender Gods generate gems, this is documented in their flavor text and in Dom3DB with the gems(X) ability under Special.

What else generates gems?
The ritual Summon Sea Kings Court summons a Sea King who generates one water gem per month. This is undocumented.

Are there any other summons (or other things) that generate gems?

So far;
Summon Troll Kings Court W3 55 gems
- Sea King produces one water gem per month

Bind Demon Lord B9 150 slaves
- One of the (four) unique Demon Lords, Belphegor, "attracts slaves and milita". Exact figures unknown

Bind Arch Devil B4F2 99 slaves
- One of the (five) unique Arch Devils, Barathrus, produces one earth gem per month
- One of the (five) unique Arch Devils, Furcas, produces one fire gem per month