Duke did not inform Vivian about the earrings, as the matter involves plane coordinates, and he had to exercise caution.
He was somewhat distrustful of the magic of the Wizard's Mark, always feeling that some very important information couldn't be communicated through it.
The Wizard's Mark itself is a simple minor spell, and its ability to achieve long-distance communication relies on something else.
Duke was not unfamiliar with this, having experienced things like communication towers in his previous life and possessing some understanding of the principles of communication.
In his view, the Wizard's Mark likely adopted a similar structure, thereby achieving communication anywhere within the Wizard Plane.
This means that the information transmitted by the Wizard's Mark probably passes through some communication tower-like places, and such information is likely to be intercepted by certain people.
