I've had many opportunities to RP hiding my gem, and reacting to others doing it.
- I've tdesced hiding it, and have had people ignore it, as if it was hidden, others have spotted it and reacted, some spotted it, then ooc'ed 'oops, ignore that reaction'.
-I've been around gemmed who have hidden it and I've played along, almost every time. There was one time that my char 'saw it', responded, we interacted, and only later did I see the tdesc, but the RP was already there, and (seemingly) fun for both of us, so I pretended I just saw it when they moved or shifted, instead of retconning the whole scene.
Goes literally any way that it could, depending on people involved.