Is this ring merchandise with a red seal and gold "忍" emblem exist in Naruto? This is a ring with a red seal and gold "忍" emblem.



I don't know whether this type of ring is in Naruto.

Who wears it? Is it a knockoff?
This is a ring made in the style of the Akatsuki rings. However such designs are merely inspired and have little to no bearing to the Naruto franchise itself.

I will not post links to any online vendors, but you will find many like it from various vendors if you do a cursory Google search for something like "shinobi symbol ring." If you add Naruto to the query you might get more franchise relevant.