There are very few crystals that are true indigo and an Iolite thumb stone is one of them. Here they are in blue-grey colour. Photo is a good representation. This is also wrongly called water sapphire crystal, as it is part of cordierite family and not carborundum.
This crystal creates a strong constitution, ridding the body of fatty deposits. It encourages taking responsibility for yourself, overcoming codependency within your partnerships. can open one to psychic talents and expand them as well. Why not enjoy iolite to calm an over active mind and will assist you in quitting negative addictions. Read about the geology of Cordierite.
Dimensions are approximate. Group A is the higher quality – aka more indigo. Group B of the iolite worry stones I discounted as they are not the same high quality.
We will intuit right “water sapphire” crystal aka iolite thumb stone for your needs.