Hi welcome to the forum,
Dutch miniature made late 19th century, the sword mark is a Dutch standard mark (used 1814-1905) minimum
833/1000 fineness or 83.3% pure silver and it could be sterling (925).
This mark, although malformed, looks like a maker's mark and it could be; A under(or above) a Heart, the maker’s mark for: August Heinrich Ankum, registered in Zaandam & Amsterdam 1851-c 1896, known to have made miniatures.
For Dutch (hall) marks see:viewtopic.php?f=5&t=32028