Ya, why not have gems have the capacity to hold enchantments within them from mages, they can only be use X amount of time & certain gems /metals have different capacities etc. then that would make any ring potentially useful or just good to look @.
You need enchanters to cast spells that get encased inside the gems, also the rare \"uber\" rings will be ones with everlasting enchantments cast on them, they should be rare, & maybe only GMs can create such items who knows...
But every gem should have some sort of capacity to hold enchantments, maybe the ring explodes if it can\'t hold the enchantment. to powerful may make it randomly discharge or something....
Maybe some rings make special effects for your Char such as streaking or particle effects maybe even skin color modifiers the potabilities are endless,
Also, You Must Be Able To Ware 10 Rings @ Least! we have 10 Fingers Why Can\'t We Ware More Then One Ring Per Finger?
Maybe you can only equip 2 of the kind of rings that have effects to limit uberness, maybe modifiers are not worth much unless you have lots of them? there are ways of having more then 2 rings on a char!
Btw, gems should be able to be re-enchanted after using...
To elaborate on my sealing idea, you have a metalsmith carve an insignia on your ring (you make a custom graphic black/white) then you can melt wax on a letter & place your ring on the wax to put your own special seal on it, then if you look @ the letter you can say \"yep this is from \" maybe a great RP stuff like a family insignia handed down from generation to generation or guild insignia \"Guild ring\" maybe there can be Crystal smiths that carve seals onto rings...