Recharging Ioun Stones?

[Rechan]

My Pcs have been finding dull grey ioun stones in various things (broken clockwork, etc) and have deduced they are magical batteries that have run out of juice.

That in mind, they are wondering how the stones could be recharged with power. Which is a decent question.

I haven't read the whole AP and surrounding content on Azlant, is that a thing that is already mentiond?

[GM Netherpongo]

I only have books 1-4 so far and I could have missed something, so consider my answer to have huge asterisks next to it...

but I haven't seen anything like that. I'd have hoped that this campaign would at least have elements of opening up ioun stone technology, but it just doesn't. There are some ioun memory nodes scattered around & the ioun gauntlet, but those are just iterations of a still mysterious magical technology. No big revelations that I've seen.

[David knott 242]

About the only thing I can think of doing with these items is use them to give a small discount when crafting new Ioun stones from them. Maybe let the discount be in excess of the price of the dull grey stone, but not by too much.