Looks like it's in a silver mount, with a ruby cabochon insert. Can we assume it's bronze, or at least a copper alloy?
A very nice piece! The legends on this coin are in nagri characters and reads "Shri 5, Bhavani, Nepal Sarkar, 1959" and translates to "(Issued by) Shri 5 (Mahendra Vir Vikram Shah deva) (with blessings of goddess) Bhavani, the government of Nepal, (Vikram Samvat) 1959" This is one paisa coin and if I remember correctly, the king's name and denomination is written on other side. Regards Ballabh Garg