The glass is stained and all the glass vases are of the strong glass type borosilicate. This type of glass is known from laboratories, as it is glass that can withstand high temperatures, is scratch-resistant and can withstand acid.
With the choice of this type of glass, you therefore have a product that can last for generations and which does not lose its color. If your vase gets dirty and gets limescale, it can be easily cleaned with hot water and sulfo – and it also withstands vinegar that easily removes limescale.