Hi,
Hungarian Assay Office offers historical import marks in PDF format.
https://www.aurumzaloghaz.hu/kepek/file/K18671937.pdf
EZÜST (silver) is on the right.
ARANY (gold) is on the left.
The import mark with assay office letter within the mark (seen in your pendant) was used throughout Austria-Hungary Empire from
1872 – 1902. It contradicts the information found elsewhere (1891-1902) but this is the most reliable document I have found so far.
Meaning, your locket can be dated 1872-1902.
Regards