Warbringer Encase in Jade skill. Unable to increase quality from Gem Prisms.

Exactly what it says in the title.
After obtaining the Encase in Jade skill, holding down the tool tip. it states, by adding quality "Buff can take 0-70 damage taken per jade consumed"

When using a Gem prism it doesn't give an option to use it on the Encase in Jade skill.