Hello Tom,
I thank you for moving the article to this place and for the interesting link to the Museum Bredius website. I think, you are right with 1806. I never would have expected, that it is so difficult to date an object when there exist a date letter system.
I have looked for Amsterdam marks in the internet and I've found, that the design of the date letters in different series is unfortunately not very variabel.
Probably the there is a system in changing design of the city-or lion marks. But I have not yet found it. The oldest exampel of the same simple Amsterdam city mark with a diagonally cuted right upper corner I have found in the internet is from 1799 (in the time of the date letter series from 1785 to 1807).
Sometimes I read, that the form of the date letter mark (round or oval) was used for dating an objekt. I have two spoons with the same mark but the stem of one spoon later was made thinner and so the marks were compressed. The round date letter mark became oval. Later added and not compressed is the crowned O mark from 1807 for older silver.
Kind regards,
Ringo

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