Soviet silver: Help identifying marks

The Basics... Identification Help - What is it?
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Hello
Novice here. Can anyone help with this vintage brooch? Markings on back look like they net be Russian/Soviet Union? I can understand the 875 mark for silver content but would like to know what the other marks are.

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I
Thanks so much

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Thank you! So helpful.

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Is the silver mark that looks like KfK on the brooch Russian for the artistic cooperative Kublachi? A bit confused because the Kublachi marks are noted as KXK? Are KfK and KXK the same? Or is KfK a different maker? Thank you.