When Blue gemstones such as Blue Topaz or Blue Sapphire are worn they have an activating effect on the forehead chakra.
When a blue gemstone is worn the blue energy helps reduce the size of the solar plexus chakra, and ajna chakra so one can relax.
Be sure not to wear a blue stone all day long if your'e already spacey or not rooted. For rooting grab a garnet ring.
You can wear a blue stone to help relax after a hard day, or to help open up the clairvoyance during healing sessions.
See some example below.