Hi Caramba, welcome to the forum.
The miniature appears to have the city guild mark, the Crowned St. Andrew's crosses, of Amsterdam and the Crowned V; duty mark for foreign and other untaxed objects used 1814-1893. This duty mark does not give any guarantee of a precious metal standard of fineness. This mark has been used on metal with a 250 minimum silver content as a duty mark. This mark was destined for all imported, unmarked and invalid marked objects of foreign, national and unknown origin. Upon the invalidation of the hallmarks of Louis Napoleon’s kingdom of Holland and those of the French Empire in 1816, this mark also has been used as a tax free census mark. The third and partial mark
(?B?) could be the maker’s mark but I am unable to identify the maker. Before 1734, silver of 2nd Standard; no date letter was stamped but only the city mark of Amsterdam; for more info see;
viewtopic.php?f=5&t=28590"
Amsterdam.The broad line in the middle is a proof- strike made by the assayer where he removed some silver to determine the minimum fineness.
Résumé; your miniature guild city mark of Amsterdam, 2nd standard in Dutch ‘Kleine Keur’ at; tien penningen or (833,333 / 1000) minimum fineness or 83.3% pure silver and probably made around the turn of the 17th- early 18th century and maker’s mark unidentified.
Oel