The language of mandalas speaks through symbolism expressing what lies in the unconscious - our 'unknown' knowledge. 
Lapis blue in ancient times resembled the blue of the heavens symbolising our expansive understanding, intellectual analysis, problem solving abilities and the creating of new ideas. This blue is about order and a strong sense of morality/laws. A powerful colour for activating the higher mind and enhancing intellectual ability, it stimulates the desire for knowledge, truth and understanding, and aids the process of learning.

Blue is associated with the throat chakra and represents spiritual connection; it symbolizes self expression, the teller of truth and clear communication. 

Images - 'Hecate' by Tiffany Ashman and 'Loss' by Anna Mow.

“The most beautiful experience we can have is the mysterious. It is the fundamental emotion that stands at the cradle of true art and true science.”
Albert Einstein, The World As I See It