I was re-watching “A Spy in the Palace” and noticed two things which I hadn't noticed before.
First of all this is adorable.
Second of all, isn’t it weird that Victor just happened to have this picture of Queen Lucia’s tiara in his coat?
Now it doesn't seem like something that he could have just found in the palace when he went there, or gotten from someone in town. It also seems unlikely that Shuriki had it, because why would she store a picture of the tiara in some secret place to retrieve later, when she could have just done the same with tiara itself.
So my theory is that Victor drew this himself. (It would explain where Carla got her artistic talent from).
It is definitely a very good drawing (In some ways, it's more detailed than the actual tiara)