Goldstein wrote: In any case I have never found any import marks on these objects - maybe they were removed.
The marks on goods imported to Russia has been discussed before, please read these links:
viewtopic.php?f=24&t=44657&p=129409&hilit=Imported+goods#p129409 and
viewtopic.php?f=47&t=35603&p=93425&hilit=Imported+goods#p93425Please use the search function and you will find more. The same fact can be found in Postnikova #56 and #57
Nonetheless, on the picture you show is clearly seen the first Russian import mark implemented according to the Assay Charter of February 9, 1882 and was used to the beginning of 1899. Your spoons are clearly imported. However, for a long time it was believed that the the letters ПТ on the hallmark was an unknown assayer but then it became clear that they meant "ПРИВОЗНЫХ ТОВАРОВ" i.e. "Imported Goods". As from 1899 a new import mark was implemented, a standing oval kokoshnik with a cut lower end looking left. As from 1908 a similar kokoshnik but looking right. In 1927 the again the same mark but with a "rabotnik" and promille.
Before 1882 imported goods can be identified having only a hallmark but no maker's mark. This is also explained in the first link above. Sometimes imported goods didn't have any maker's or export marks marks at all. Sometimes as well a hallmark, no maker's mark but the importer's trade mark or logo.
.....or do I misunderstand something in your wondering?