It does irk me honestly that you can get a full set of gear from a raid tier or a set of tome gear etc except for one ring, but it's not really a big deal to me. It just makes me feel slightly ocdish I guess? Something that irks me slightly but isn't really a problem.

As far as making rings match visually, if your armor set even has them visible without hiding your gloves just glam one of them. If you mean it not matchign the other pieces on your character screen nothing you can do about that.