I sealed mine with clear nail polish no complaints. Although if I could go back I might not have sealed it since I like how the stone felt. My other jnat is sealed with something called liquid glass I believe, it came sealed so all I can do is show you how it looks.
Image of bottom of stone with liquid glass.
If it's just lacquer/nail polish, put the stone in a ziplock bag and soak it overnight in isopropyl alcohol. Should come right off.