Natural Glass Beads Strands, Grade A, Round, Undyed, Aqua Blue, Size: about 20mm in diameter, hole: 1.4mm, about 20pcs/strand, 15.5~15.7 inch(39.37~39.88cm).Natural glass is a type of glass that forms in nature without human intervention. It is created when certain types of rocks or minerals are subjected to high temperatures and pressure, such as during volcanic eruptions or meteorite impacts. natural glasses often have unique properties and characteristics due to their formation process.