Is there a way to modify this ring to replace this tiny diamond with a larger diamond?...Maybe a 1/4ct diamond? It was my great grandmother's and I would like to replace the existing diamond with one I have from a pendant.
I would honestly just leave the ring be as a keepsake of your grandma. Since the setting is old, it could get damaged during modification to its structure. What about designing a replica of the ring but with a bigger diamond?