How do I add gems to a ritual spell?

[BigJMoney]

I can't seem to find the answer to this question. I'm sure it's something obvius in the interface which I've missed.

=$= Big J Money =$=

[sushiboat]

When you cast a global enchantment or other spell that can use additional gems, you will get a dialogue asking how many gems you want to put into it. There are up and down arrows to adjust the gem number.

[Molog]

Pressing + and - works too.

[magnate]

... but once you've cast it, that's it. You can't go back and boost it with more gems later.

CC