Belying their delicate appearance, the glasses are in fact heat resistant as well as microwave and dishwasher safe. Their durability lies in their material: borosilicate glass. Borosilicate glass is created by adding boron to the traditional glassmaker's frit of silicate sand, soda, and ground lime. The result is a glass that is highly resistant to thermal shock, making it suitable for a variety of industrial and scientific uses. The form of the glasses themselves is elegant and minimal, and never overshadows the color and character of the beverages that they contain.