Kostroma silver ring maker

[timmthaler]

During gardening I found silver ring. I identified, that it was made in Kostroma 1880-1890 http://www.925-1000.com/Frussia_city_03.html.
Unfortunately I can't find maker whose initials are "ГСТ" (latin GST). Can someone know whose behind these initials?
http://www.hot.ee/t/thaler/IMG_5771b2.JPG
http://www.hot.ee/t/thaler/IMG_5776b.JPG

(admin photo edit - images too large - link only - see Posting Requirements )

Big images:
http://www.hot.ee/t/thaler/IMG_5771a.JPG
http://www.hot.ee/t/thaler/IMG_5776a.JPG

[timmthaler]

(admin photo edit - images too large - link only - see Posting Requirements )

It is confusing, if forum configuration is different (max 1000px), than forum rules (18 cm = 680 px). Smaller images according to forum rules

[Zolotnik]

Hi timmthaler -
the maker ГСТ is still not identified until today.

Regards
Zolotnik