Rhodenite and Silver, vintage 1953 Sverdlovsk Ural Brooch. With a trombone clasp. Markings are Урал СЮ3  and c followed by the Soviet star (hammer and sicle) and 916 silver hallmark. This is a rare treasure, not only of asthetic beauty, but also for it's historic significance. 
The city Sverdlovsk (existing 1924-1991 took back it's name Yekaterinburg) was named after the Bolshevik leader Yakov Sverdlov. Sverdlovsk was one of several places developed by the Soviet government as a centre of heavy industry. Old factories were reconstructed and new large factories were built, especially those specialised in machine-building and metalworking. 
The Urals have been viewed by Russians as a "treasure box" of mineral resources, which were the basis for its extensive industrial development. In addition to iron and copper the Urals were a source of gold, malachite, alexandrite, and other gems such as those used by the court jeweller Fabergé. 
Brooch Measures 1.625" ( 4.127cm) Width by 1.25" (3.175cm) Height