What color does anhydrous cobalt(II) chloride paper turn when it comes into contact with water?

Anhydrous cobalt(II) chloride is a blue solid that changes color when it absorbs water. When it comes into contact with water, it undergoes a hydration process, transforming into cobalt(II) chloride hexahydrate, which is pink in color. This property makes cobalt(II) chloride paper an effective indicator for the presence of moisture: it is originally blue when dry but turns pink when it is exposed to moisture or water. This color change is due to the different arrangements of water molecules in the hydrated form compared to the anhydrous form, altering how the compound interacts with light and hence its perceived color.