Commitment rings, matching or not?

I’m wanting to buy a commitment ring for my gf, but not sure whether just to get her one, or is the norm to get matching pairs for me as well.. I’m not sure as I’ve been to the jewellers and found one for her that I want. Only thing is there are some diamonds on it, is this acceptable for a commitment ring? (the jeweller told me its under the catalogue as commitment ring). how are they different to a engagement/wedding ring (which we’re not quite ready for). Do they look different or anything? also, is it something that I can just pick out for her? Do they have stones/no stones? Thanks in advance.
Sorry, by matching, I mean do I need one? or can I just give one to her and thats it?
The one I’ve got in mind looks similar to this, but probably alot smaller is this acceptable?

I am assuming a commitment ring is a promise ring which is worn on the right hand. I think it’s a really nice gesture you dont have to have one matching you dont have to have one at all. It’s the bridal sets that should match but not even my fiance and I have differ ring mine has diamond his is a plain band. The difference between promise and engament ring the promise is worn on the right hand engagement left and ussually if there is any diamonds the engagement has more. Look into rings by prmise or try took look up her birth stone.

Diamond Matching Pair
Diamond Matching Pair
Diamond Matching Pair