The crystal was possibly glued on with jewelry glue, maybe not. So the only idea I have, is using alcohol is soften the glue, then using dental floss or a fine thin wire. Run the floss or wire behind the crystal and gently remove. You do not want to scratch the glass. Save the crystal for a future craft. You could also not got to all this trouble, and put a votive candle or candy in the glass, tie a ribbon and bow around it and give as a gift to a friend, an acquaintance or delivery person. They would appreciate your thoughtfulness.
The crystal was possibly glued on with jewelry glue, maybe not. So the only idea I have, is using alcohol is soften the glue, then using dental floss or a fine thin wire. Run the floss or wire behind the crystal and gently remove. You do not want to scratch the glass. Save the crystal for a future craft. You could also not got to all this trouble, and put a votive candle or candy in the glass, tie a ribbon and bow around it and give as a gift to a friend, an acquaintance or delivery person. They would appreciate your thoughtfulness.