Wisdom to Mana conversion ratio?

[htabdoolb]

I've been looking for the conversion ratio for WIS to mana for a while now, and haven't been able to find one. Does anyone know if one exists, and where I might find it? It seems the stamina to hit points scale is pretty well know, so I was hoping that a wisdom to mana one existed too.

I'm wondering mainly because I'm curious at what point a piece of gear with +WIS becomes better than a piece of gear with +mana. For example, I'm wearing two different rings, a +6 wis jewelcrafted platinum jasper ring, and a +3 str +30 mana moonstone ring on my level 41 cleric. Are they about equivalent, or is one better than the other in terms of pure mana? And at what level might that change?

Thanks for any info!