Silica Gel Blue semi-transparent glassy substance containing an indicator as “Cobalt Chloride” a heavy metal salt. When free from moisture the Granules or beads are dark blue in colour. As the beads take up moisture, they turn to light blue gradually & When they turn pink, When the gel has absorbed approximately 8 % percent of its weight in water the coloured crystals will turn from blue to pink making an easy visual indicator of whether the gel has become saturated with moisture. It indicates that the gel needs to be replaced or regenerated.