You know, I started to reply to this thread back when it was originally posted. No idea why I didn't finish it.
Anyway, I don't think this has ever been considered, or requested for that matter. Since I believe the glow is tied to the soul of the one who imprinted upon it. So if that's the case, I'd estimate that the glow would fade within 3 days.
I'd say also that the stone remains otherwise intact but inert.
That's just my guess, however. EdTheKet may find cause to disagree with or simple refine my answer.
