Notes
The formula for determining how much damage is absorbed is:
where
The damage absorbed from the spell is capped at 350. However, receiving the Stoneskin effect from this spell while equipped with Stone Gorget adds an additional 30 damage absorbed, and Stone Mufflers adds another 30. These additional "HP" are not limited by the spell's natural cap; when Stone Gorget and Stone Mufflers are used together, the maximum total damage absorbed by the Stoneskin is raised to 410.
Note that when cast as Accession Stoneskin, enhancing "Stoneskin" equipment must be worn by the receiver in order to take effect--a Scholar cannot give Stoneskin above 350HP to people who are using neither Stone Gorget nor Stone Mufflers.
source