Silica gel blue is a semi-transparent glassy substance that contains an indicator called When free from moisture, the beads are dark blue in colour. As the beads take up moisture, they turn to light blue gradually and then they turn pink, which indicates that the gel needs to be replaced or regenerated. In fact, it is mainly used as an indicator of the extent of dehumidification and moisture adsorption in a sealed vessel. Silica gel is available in the form of crystals and beads according to the user's application.