Glass and copper have the same coefficient of thermal expansion, and that makes it posible to combine the two materials. The glass is blown through the copper rings, hereby the copper ring defines the shape and becomes a part of the object.
The patina of the copper becomes dark because of the extreme heat during the glassblowing process. However the pieces can be polished to make the copper shine.
The glass is blown by the glass artist and my teacher Diego Vides Borrell during a glass blowing course at Xaquixe. Xaquixe is a sustainable glass factory in Oaxaca.