Not only ruby, but the emerald also had the reputation of being a luminous stone, carbuncle or rubies shone with their own light. Yellow diamonds are luminous. The power of absorbing sunlight or artificial light and then giving it off in the dark is only possessed by certain diamonds. Diamond is one of the most valuable of precious stones. This is also the hardest.The diamond is to the pearl as the Sun is to the Moon and we might well call one the "king gem" and the other the "queen gem". Diamond symbolised fortitude corresponding with the planet Saturn . Diamond consists of pure carbon and may be of all colours. Black diamonds occur, and not all are inferior. Other colours are blue, green, yellow, rose and brown. 

The Hindus believed that a flawed diamond, or one containing specks or spots, was so unlucky that it could even deprive Indra of his highest heaven. A triangular stone was said to cause quarrels, a square diamond spired the wearer with vague terrors, a five cornered stone has the worst effect of all, for it brought death; only a six cornered diamond was productive of the good. In the older form of the tale, the stone grows either, pale or red as a sign of misfortune. Of course, to lose a diamond was very unlucky. Diamond grew dark in the presence of poison. Diamond enjoys in India the reputation of being especially auspicious. It happens often that the good diamond loses its virtue by sin and for incontinence to him who bears it. 

According to a widespread superstition, the talismanic power of a diamond was lost if the stone were acquired by purchase. Only when received as a gift could its virtues be depended on. The same belief is noted regarding turquoise. The spirit dwelling in the stone was thought to take offence at the idea of being bought and sold, and was supposed to depart from the stone, leaving it nothing more than a bit of senseless matter. If, however, the diamond were offered as pledge of love or friendship, the spirit was quite willing to transfer its good offices from one owner to another. Ancient lore says that, as a talisman, the diamond was valueless, when it had been stolen, sold to taken by force or fraud. The mystical power of the gem would work only where it had been freely given. 

Most of the writers of antiquity favoured the wearing of the diamond always on the left side of the body. This gem possesses the most marvellous virtues. It gives victory to him who carries it bound on his left arm whatever the number of his enemies. Pains, pestilences, enchantments all fly before it. Hence it is good for sleep walkers. It was also much favoured as a safeguard against insanity, and constantly worn, promoted constancy in marriage. 

As a healer, both in the physical and mystical sense, the diamond was used extensively in ancient and medieval days. The stone's power of irradiating light of peculiarly pure quality probably accounts for its suggested ability to protect against witchcraft, evil forces and satanism. In India, it used to be the custom for wealthy parents to sprinkle tiny diamonds over the head of new born infants

Throughout history, it has been one of the most valued /stones for its healing and protective powers. Since ancient days, the colours green and blue have been traditionally associated with healing and it is scarcely surprising that the healers of old ascribed great value to this stone which rivals the brightest and most radiant greens found in nature. In India and the Far East , too,emeralds were ascribed almost god-like powers of protection and healing. It was believed to be an antidote against evils of all kinds. In the presence of an emerald worn upon the person, intended treachery or bad faith could be discovered, for the jewel would immediately give warning by turning pale, just as rubies change with ill-health and topaz with poison. It had the dramatic power, too, of being able to hurl itself from its setting when misfortune threatened the owner. Emerald symbolised sympathy or understanding parallel with Venus. It was the stone of the planet Venus. It is said by gazing at the emerald, one improves the eyesight. 

Emerald was employed as an antidote for poisons and for poisoned wounds, as well as, demoniacal possession. If worn in the neck, it was said to cure the "semilertain" fever and epilepsy. Furthermore, the wearer was protected from the attacks of venomous creatures and evil spirits are driven from the place where emeralds are kept. 

In this manner, the emerald was variously recommended to quell tempests, consequently it can restrain passion. It favours the functions of the liver, produces bile, relieves dysentry, and promotes child birth. In this connection, too, it was thought to protect, in a mystic sense, a woman's chastity and to preserve the love and esteem of her husband. 

To the healers and wise men of old, the emerald was always something more than exquisite jewel, having proved therapeutic powers, It was a talisman, a link with spiritual forces. 

In Hindi garnet is known as Yakoota or Raktamani. Its hardness is 7.5 and Sun rules over it. It is believed that it is useful for all those who have their Ascendant or Rasi (Moon sign) or the Sun sign as scorpio / Aquaruis or Pisces It is specially useful for those who have Sun, Moon and Ascendant identical as above.Garnet is found in various colours from deep blood red to almost dark. It is difficult to distinguish the genuine from the artificial. Gomedak is a cheaper variety yet it has its own place in the gems. 

Garnet is not formed of anyone single mineral but a mixture of many. Different proportions in which they form the stone explains the difference in various varieties Gomedak is also of different colours. It is found in India also but its colour is mostly pink.