The ring originally was a seer event item. Or an item created uniquely by some seer or GM ages ago. Waaaayyyyy before magic moments. I knew of one on Atlantic before X-sharding ever existed. A friend of mine owned it at one point.
There are several problems with calling it "unique".
1. I knew of one on Atlantic like I said before x-sharding. So if someone from another shard can claim to have seen/known of its existance on their shard, there goes the unique claim.
2. There were tooooooons or unique rings made on each shard way back in the day years and years ago. For guilds, friends of GM's/Seers, old old weddings. (Not magic moment ones. Actual in game weddings that Seers/Old GMs attended when they had a lot more liberties to go have fun with the populations of their shards).
3. Anyone could very well have bought one of the more recent Magic Moment packages. Wedding, Halloween, random party or whatever. And if it was a Wedding you obviously got 2 rings you could uniquely name (Someone could easily have asked for "Queen of Thieves/King of Thieves" ring set). There would be 0 way to distinguish if it was a silver ring and blessed. And even if they didnt purchase a wedding package. When you bought any other package the GM who ran it (or whatever their title is, party thrower, etc). Would give you a uniquely named item, or wedding gifts, party favors). The possibilities are endless.
Could it still be unique/1 of a kind. Possibly. Is it likely? I would imagine there is a handful of them out there. Resulting from any possible combination of the above sources.
A Stoned Mariner...W$R...Atlantic.