Need help identifying a symbol on the back on a seal ring

[Selenity]

This seal ring has been in my family for many generations and I only recently saw the symbol on the back and have no idea what it means. Hoping someone can help me with this.

[KGarrad]

Probably a maker's mark?

Not enough to be hallmarks.

[davidgp]

Could be a standards mark noting the quality of the silver (if it is silver)

[Viktoria]

Can you see what the marks are? The photographs is not clear enough.
One mark 585 is for 14 carat, but there would also be a crown before the numbers.
Viktoria.

[Selenity]

Took a magnifier to the ring and it looks like numbers 90? I cant make out the last number.

[manukarik]

Probably 900 meaning 90% pure silver.

See:
https://en.wikipedia.org/wiki/Fineness

[farmeroman]

I’m not sure if it’s gold or silver, but I think it’s a metal purity mark, so 90%, which would equate to roughly 22ct gold. Possibly foreign made hence the lack of hallmarks.

[Selenity]

It is gold.

[farmeroman]

It is gold.

I’ve seen a gold ring online with 90% stamped on it. The 3rd symbol on yours doesn’t look like %, but it could have the same meaning.