Can anyone please help identify this Russian marking?

[Belle86]

This ring was handed down to me by my grandmother, it was her wedding ring, it is engraved with her name and date (1939) but I believe the ring was also handed down to her and I have tried to identify the initials (Russian гc) and the only Russian jeweler I could find from the era was Grigory Sbitnev, but when looking at his stamp, it looks slightly different, so I am not sure, also it seems to lack other stamps, like the city stamp etc. If anyone is able to lead me in the right direction, I would appreciate it. Thanks.

 

[gemcuba]

Hi, 56 zolotniks is equivalent 14kt gold, and 72 zolotniks for 18kt gold, A zolotnik was a small Russian unit of weight, equal to 0.1505 avoirdupois ounces, or 4.2658 ... the ratio zolotnik/funt was meant, so one zolotnik meant 1/96. For example, 14-karat (58.33%) gold was named "56-zolotnik gold" in Russia.