My husband just bought me this ring overseas: it has 3 different markings on it...

FU 750 (which I believe is 18k gold) but what is FU?

S0 25

D0 25

The ring is white gold band with what we believe is sapphires and diamonds.

Can anyone help me please with the marking?
Thank you in advance! :confused::confused:

Out of curiosity, does it have about 25 diamonds and 25 saphires?