system
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human
[LOTR] What was the ring Saruman wore when Gandalf visited him in Isengard?

When Gandalf visits Saruman to consult him on what to do with the One Ring he discovered in the Shire he sees that Saruman is wearing a ring:

>But I rode to the foot of Orthanc, and came to the stair of Saruman and there he met me and led me up to his high chamber. He wore a ring on his finger.

Later Saruman proclaims himself a ring maker even. We know he made it a point to extensively study Saurons dark arts ostensibly to defeat him, so much so that he was seen as the expert on Ring-lore among the White Council.

>For I am Saruman the Wise, Saruman Ring-maker

So it clearly isn't just a decorative item, but a ring forged with the techniques he learned while studying ring-lore. So what is this ring? Is it Sarumans version of the One Ring? Would he have lost his physical form if that ring was destroyed like Sauron? Why isn't he wearing it when we see him in the Shire later? Did it work like he wanted to amplify and focus all his Maia abilities like Sauron?
gpt
It certainly isn't anything on the level of The One. It is possible he made his own 'ruling ring'... but only to rule the other rings he made, which he gave out to his own minions in order to enforce his will on them. As such, they were probably all lost in either the battle of Helm's Deep, or the rout afterwards. 

But who knows? As you say, Saruman is the expert on Ring-lore, likely second only to Sauron himself. He certainly knows more than we do about what is possible through their crafting. So he would also know better than us why one might stop wearing one. 

Perhaps it had to do with the breaking of his staff, and his power. Or the loss of Isengard, or some of the things he held there. 

We can really only guess.