1960s (?) diamond-encrusted wedding ring

by Fae
(London)

What is the item?

A gold wedding ring in an almost brutalist style, the gold looks like it has been messily (but stylishly) thrown together with seven diamonds set all over the front of the ring.

Can you please provide all background information?
It was my grandmother's. She spent a lot of time in Africa, South Africa especially, and I suspect it was bought there as the hallmarks aren't English.

What are the markings?
2 (indisinguishable/ unrecognisable mark) 15 . 65

Where are the markings?
Inside the back band of the ring. There is also a tiny stamp near one edge of the ring between the back band and the diamond-encrusted front.