If you're looking for a hookah bowl that's truly unique, then you'll want to check out Kolos hookah bowls. Each one is handmade, and the glaze is applied by hand, which gives each one its own distinctive look. The glaze is made by German manufacturers and is designed to improve water permeability and give the bowl a characteristic shade. The main material used in the construction of these hookah bowls is white and red clay, which undergoes a process known as "milking." This involves treating the bowl with milk at a temperature of 200-300 degrees. This treatment helps to improve the water permeability of the clay and gives it a unique color.