If a customer would like to hold a vase to experience its weight and scale, remember to ask them to remove their rings and watches first. If the piece slips in their hands a ring or watchband can scratch the surface.
Also watch for zippers or buttons on clothing that can damage the surface.
Always clean the glass with a very soft cloth. Over time, paper towels may faintly scratch the surface of a vase. Also, use a mild windex/vinegar combination or a diluted rubbing alcohol/denatured alcohol as a cleaning agent.
The ground surface areas on a vase can become “dry”. Use a small amount of mineral oil on the end of your fingers and gently rub the ground areas in a circular motion. Wipe the excess away with a soft, clean cloth.