After farming Adjorjan for watermark i experienced the following iteraction with watermark and loot drops. I have concluded that adjorjan’s WM cap (Level 62) is 565.
When progressing from 500 GS towards the 565, is get consistent drops which are +/- 5 of my current watermark for each item. As such if i am 530 i will always get a 525 - 535 watermark range for this item. However this changes when you get towards the 565 GS cap. When i reached 562+ i begun to see that gear drops were now around the 500gs mark as if the watermark had reset. After testing this with multiple gear slots i have come to the following conclusions.
When you are close to the WM cap the game still rolls to determine the GS of the gear. However if the game rolls over the WM cap for that particular boss then instead of rolling around your watermark, it calculates the GS at the 500 GS more and applied the GS increase that rolled. Example, if you have a 562 watermark for body armour, and then the game determines you should get +4 GS this takes you over the monster cap and you receive a 504 body armour piece. There is also another interesting interaction, that you now begin to get GS increased based on this new watermark feature. However every now and then you get drops at the higher GS number.
The positive of this feature, is that it kind of shows you when you are reaching the watermark cap of a certain enemy. Handy during the experimental phase of the game.
The negative of this feature, is that if you are farming for a high watermark unique/legendary from a certain boss and you have increased your WM specifically for it. You may receive a way lower GS item than what your watermark is due to this.
Would love some further clarity around this.