Vintage 925 sterling silver Viking Medieval style minimalist scarf shawl pin

Vintage sterling silver pin. Stamped STER. and has a partially visible makers mark. 4 cm in diameter. Looks like a medieval Viking scarf shawl pin. Can also be used as an "O" brooch - on hats, Ciara, jackets, sweaters... The front surface is frosty, with some wear, as pictured. Otherwise in excellent fully working condition.