How to Make Hereafter Stones
The first step to making Hereafter stones is to get your hands on some raw stone. You will need at least 18 to make 10 Hereafter stones; once you have the minimum amount of raw stones, you need to craft them into stone bricks at the stonemasonry workshop. Three raw stones will make a single stone brick.
Once you have six stone bricks, you then need to get a single Onyx Archeum Essence. Again you can buy it from the auction house, and in this case, I would recommend doing that. The reason is that to get Onyx Archeum Essence; you will need to deliver cargo to a cargo exchanger, which means cross-sea trading. This is time-consuming and really not worth it if you are only interested in getting Hereafter stones.
Finally, when you have six stone bricks and a single Onyx Archeum Essence, you can find a stonemason workbench and make ten Hereafter stones.