Gemstones for planets are considered as effective for the planets. The gemstones for planets are believed to eradicate the negative effects of the planets and their positive effects are also enhanced with the help of the gemstones. As per principles of Vedic Astrology, gemstones are associated with nine planets, namely Sun, Venus, Mars, Mercury, Jupiter, Saturn, Rahu, Ketu and Moon. Some of the popular gemstones for planets are as follows;

1. Blue Sapphire is the gemstone for Saturn planet,
2. Cat"s Eye is the gemstone of Ketu planet,
3. Coral is the gemstone for Mars planet,
4. Pearl is the gemstone for Moon planet,
5. Gomed is the gemstone of Rahu planet,
6. Emerald is the gemstone for Mercury planet,
7. Ruby is the gemstone for Sun planet
8. Yellow Sapphire is the gemstone of Jupiter planet, and
9. Diamond is the gemstone of Venus planet

These are also revered being as "Navratnas". All the gemstones of planets are described below -

Blue Sapphire, Gemstone for Saturn: This gemstone is of Saturn and it is said that this stone basically rules the western direction. Blue sapphire gemstone is a composite of oxygen and aluminium and it turns blue after the compound is mixed with cobalt. Blue sapphire must be worn in the middle finger and it should be embedded in silver or iron ring.

Cat`s Eye, Gemstone of Ketu: This is the gemstone of Ketu. The corresponding sign of Ketu is Pisces. This gemstone has white coloured lines over it that resembles the eyes of a cat. Cat`s eye helps in bringing courage, contentment, vivacity, ecstasy, etc. It is advised that Cat`s eye gemstone should be worn in a middle finger and its weight should be at least 3 Ratti.

Coral, the Gemstone for Mars: This is the gemstone of Mars planet and its zodiac signs are Aries and Scorpio. Coral is actually a type of organic substance that is prepared by a non-vertebrate sea creature. Coral gemstone is said to ward off fever, piles, abortion, typhus, small-pox, etc. A coral ring should be worn on the ring finger and before that it should be embedded with gold or copper.

Emerald, the Gemstone for Mercury: The zodiac sings under the ruling planet Mercury are Gemini and Virgo. Emerald is the gemstone for Mercury planet. This gemstone is basically a mineral, a compound of oxygen and silicate of aluminium beryllium. Wearing emerald helps in soothing mental commotion. It also enhances logical power as well as spiritual power as well. Emerald should be embedded in silver rings or five metal rings before wearing them.

Gomed, Gem stone of Rahu: Gomed gemstone is for Rahu planet as this planet has tremendous influence in a person"s life. This gemstone is also known as Garnet. A person, who is afflicted by Rahu, faces mental tension and disruption in his business, conflicts, etc. This gemstone should weigh a minimum of 3 Ratti. It should be worn on middle finger and must be embedded in silver or five metals ring.

Ruby, the Gemstone for Sun: Ruby is the gemstone for Sun planet. It is advised that Leo people should wear this gemstone. It can also be worn by those whose horoscope has a weak sun`s position. Wearing of Ruby helps in eradicating scarcity; it also endows opulence, name and fame in the political sphere. Minimum weight of Ruby should be at least 3 Ratti and this gemstone should be worn on the ring finger.

Pearl, the Gemstone for Moon: Pearl is the gemstone related to Moon, which is the imposing deity of the element water. Pearl is a combination of oxygen and calcium. Minimum weight of Pearl should be 2 Rattis. This gemstone must be embedded in a silver ring or pendant and should be worn on right hand"s smallest finger.

Yellow Sapphire, the Gemstone of Jupiter: Yellow Sapphire is the gemstone of Jupiter, which is the largest and heaviest planet. This gemstone is basically a mineral, in which mainly hydrovisil, aluminium and florin are present. It is said that the wearer of yellow sapphire receive an understanding of morality, sense of humour, law, etc. It should weigh a minimum of 3 Ratti, must be worn in the first finger and should be embedded in five metals or gold ring.

Diamond, Gemstones for Venus: Diamond is the gemstone of Venus planet, which is the planet of love, arts, romance, beauty, harmony and understanding.

Thus, it is firmly believed a correlation exists between each planet and its correspondent gem.