If silver contains 7.5 % other metal, one can use a ring made of it (provided it is not more than 4.372 gm), because in this case the ruling of silver shall be applicable on it by considering the 7.5 % metal as silver. It should be noted that the permission of silver for male is limited to ring only. It is not allowed for male to use other silver jewellery instead of ring.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband