Miijo Crystal water bottles are approximately 550ml. As crystals are a natural product and each crystal may be a slightly different size and take up more or less room in the bottle.Our bottles are Borosilicate glass, which is less subject to thermal stress then other glasses. The lid and base is made of either stainless steel, or sustainable bamboo. The crystal is held in place with stainless wire. The crystal is natural gemstone. Crystals are a natural resource and colours vary.