Need help to ID the maker's mark?

[adanak1]

Here are the marking on this Russian maded Jewellery. The hallmark says 84 and AB (1899) but the maker's mark (RC) I can't find anything match!
the most look's like is Yakov Borisov ? (Rb)

[Qrt.S]

It would be interesting in seeing the whole object, thank you.
Anyway, the assayer AB is Aleksandr Kasimirovitch Vyrzhikovskij who assayed in Kiev 1893-1904. Your object is from between 1899-1904 and made by a by name unknown master ЯС (YaS) who worked there 1899-1908. It is in silver in fineness 875/1000.

[adanak1]

Thank you very much! Does this unknown master produced a lot of his work? and how about the round circle mark?
Try to upload the whole object however the image was too large,will try again later!

[Qrt.S]

I really don't know, never stumbled into this master before. However, there are a few things made by him in the state historical museum in Moscow, that's all I know. The round mark with the kokshnik facing left is a part of the Russian assaying system i.e. every detachable part must carry a mark. No problem with that.

[adanak1]

Thanks again!!!!