So. my assumption was correct in regard of 12 Loth.
See above:
(Number 75 remains a mystery, if indicating sub-standard zolotniki it would be close to 12 Loth, but I do not like to speculate without reliable
references).
Well, after Dad`s comment 75 is not a mystery any more.
But 75 zolotniki (.781) is too low for 13 Loth .813 or 78 zolotniki, and too high for 12 Loth (.750).
If the beaker is 12 Loth (.750) or legal 72 zolotniki no additional mark 75 would be needed.
As it was assessed above 72 zolotniki, it must be 13 Loth, because exactly .781 would be very unusual 12 1/2 Loth.
But, were the measurements so precise at the time ?
All said, it would be interesting to test the fineness of the beaker.
(Correct me if my calculations are wrong).
Regards