![Image](https://i.imgur.com/pf5xpiP.jpg)
The 56 mark is straightforward (14k equivalent), however I am at a loss of how to interpret the "AP". I believe this is the assayer's mark, and I've seen other examples attributed to either St. Petersburg assayer Alexander Romanov, Hall Inspector from 1899 - 1908, and also to an assayer from Astrakhan Assayer Anton Vasilijevitch Richter from 1899-1916.
Would greatly appreciate your thoughts - I understand if this is an Assayer, it is difficult to say with certainty unless the maker mark can also be identified.
Here is a photo of the ring in question in case anyone is curious:
![Image](https://i.imgur.com/L086kzg.jpg)
Thank you so much for your help!