Corundum.

As very hard after diamond is mineral, of blue or red colour, rare are yellow and orange, as his kinds are ruby, Sapphire, as his old Russian name is yanond ,Corundum giving you a braveness, an own appreciations feels, as who carries his are harmonizing with a surrounding worlds, as and better knowledge absorbing, rising work capacity, good for attention, not relaxing or distracted, as helping leading are high results, fighting fears, phobias, worry, irritability,angry, as carry his of pendants , rings, earrings, as after every his carry wash in warm slightly salted water.
As depending of colour he affecting on the different chakras, as blue is a chakra of third eye Adgna  are for eyes diseases, eyes pressure, as of yellow orange Svadhistana are rejuvenating you, positive is for gastrointestinal, blue is on throat chakra Vishudha, of violet clear in psychic diseases, improving a condition feeling in the brain concussion, red is on heart chakra Anahata and navel Svadhistana chakras, as curing paralysis, pressure normalizing, and metabolism, as corundum improving for nerve system, as in schizophrenia , insomnia, depression, night horrors, as vision for, hypertension, hearty, blood circulation, osteochondrosis, aches in spine, joints, spine diseases, kidneys, liver, digestion, climax on, relieving conditions for.