These 7.62 x 54R Bullets have been made into cufflinks.
These rimmed rifle cartridges were made and used by the Russian military in sniper rifles and machine guns. And they are still in use today.
The 'R' stands for rimmed which gives them this bevelled shape.
These cufflinks come in a gift box.
Bullet diameter 14mm

7.62 x 54R Bullet Cufflinks