Cobalt Blue Transparent 16mm Glass Marbles Pack of 20 Wondertrail WONGM109 WONGM109 Cobalt Blue Transparent 16mm Glass Marbles Pack of 20 Useful in games, Glass marbles are also great for decorating vases Each bag contains 20 glass marbles 15-17mm in size. All marbles are packed in blisters for protection in storage and shipping by Wondertrail NOTE: Colors may vary slightly depending on your monitor settings.