Sunstone flat stones are loved by many people as the quality is higher than the thumb stones. They are more orange and more sparkly in the bright sunshine. Buy one to enjoy the tactile feel of rubbing their fingers along the surface is great. And the shape allows ease of putting these in your pocket, on your body, or in a hemp necklace to wear.
This is an Indian sunstone smooth stone and it seems to be sun-friendly but I have not done rigorous tests.
A sunstone flat stone like this is said to ease phobias about the dark/enclosed spaces. Attracts fame and good luck in competition, prosperity when hidden talents uncovered.