White gold ring

This ring came in a lot with 3 other rings. I bought the lot for the other rings and at first I didn't really like this one. But as I tried it on I eventually got fond of it. Now I wear it regularly, and I don't even think about getting rid of it.
It tested as 18K white gold with tiny old cut diamonds and a brilliant cut in the center. It's heavy, I think around 6grams.
Maybe one day I will change the small diamond in the middle for a bigger one. I think that would look nice on this ring.
No idea on age or origin, and there are no marks. Maybe fifties, sixties? Does anyone have a clue?