I'm pally tank and every time I kill a mob in a dungeon I need to stop to retrieve mana, so I need to invest in items that give intellect and spirit to improve it.
In Uldaman I've taken this finger:
But the priest healer became angry, then I ask you if you have already seen some priest healer with a ring that provides armor, because I play Wow for over 13 years and I've never seen.
What is your opinion about this, tank or healer ring?
Neither intellect nor spirit will solve your mana issues, use Judgment of Wisdom when you need mana until you get Divine Plea. The only tanking stat on that ring is the armor and it's a very pitiful amount.
several workaround which I assume you're playing on TBC
1. use Seal/Judgement dance, fun fact JoW base damage is higher than other Judgement
2. take Spiritual Attunement, ask healer to let your drop a bit coz you got mana return when healed (on TBC I think it only works from direct heal)