Methods for giving luster to a pearl are also described. The pearl should be placed in cavity of a fish, which is then smeared with clay and baked. The pearl should then be boiled in milk, then in water and finally in limewater. The pearl thus treated assumes an excellent luster. According to the traditional Indian belief, the human body is composed of the seven colors of the rainbow, associated with seven kinds of rays.
Diseases enter the body when there is a deficiency or excess of any ray in our body.
Each color is associated with a particular gem, which in turn is associated with a particular planet. According to astrologers, a gem is beneficial when worn in the phase of a particular planet as these stones also affect our health and destinies. Besides, there are other important characteristics of gemstones in their medicinal use. The ruby associated with the Sun is extremely hot and releases hot waves in the form of red cosmic rays. It should be worn only during the winter months.