Known as Ruby. Chunnee.  Red Spinel.  Lalree.  Maanik or Maanikya.  Padmaraag.
"The Sun manifests his brilliance in a ruby although it is a gem." [Shree Brahm Sanhitaa : 5.49]

It is one of the nine gems or precious stones. The nine gems are (1) Heeraa - Diamond; (2) Pannaa - Emerald; (3) Lal (Ruby), (4) Motee (Moonstone or Pearl), (5) Moongaa - Coral; (6) Neelam - Sapphire, Indraneel, Neelmani; (7) Pukharaaj (Yellow Sapphire), (8)  Vaidoorya Mani; (9) Gomed - all are called Mani or Ratn. The ruby is found in a variety of crimson and scarlet red colors ranging from pink to a deep ruddy violet color. The gemstone is solid and possesses high specific gravity. The red tint in ruby comes from a light combination of iron and chromium. The finest quality ruby has a delicate red color. Some qualities of a Good Ruby are - 1. smoothness, 2. Uniform Color, 3. brilliance, 4. hardness.

In the Nava Graha system of Planetary Gemology, Ruby is the Gemstone that is used to enhance the powers of the Sun. The Sun is the vital life force and represents the Soul of the Kaal Purush. An individual whose Sun is well placed in the birth chart can never be unsuccessful. He will always be in limelight whether as a Union Leader or a statesman. Ruby is not Suitable for everyone. Here are given the conditions for the suitability of Ruby for the 12 ascendants from Aries to Pieces.

Taurus Ascendant
The Sun is not an auspicious planet for the Taurus ascendant. Even if it is in Exaltation in the 12th House it will not give benefits as may be expected. Secondly it is the enemy of the Ascendant Lord Venus. Ruby should be avoided by Taurus ascendant individuals unless the Sun occupies a favorable position from the Lunar ascendant.

Gemini Ascendant
Ruby should be considered for a Gemini Ascendant if the Sun is placed in the 3rd house or the 11th house and the Sun's Mahadasa or the Sub-period is running for the individual. Also special notice should be given to the Sun-Mercury conjunction - Budh-Aditya Yog. If the Budh-Aditya Yog is occurring in the ascendant, or 3rd House, or 4th house and or in the 11th House then both emerald and Ruby be worn by the individual for special benefits.

Cancer Ascendant
In Cancer ascendant the Sun becomes the wealth-controlling planet. The best position for Soorya in this ascendant would be in the 10th house. If such a combination is occurring in the chart then Ruby should be worn. The Sun's placement in the 9th House, or 5th House will also be conducive for wearing a Ruby.

Leo Ascendant
Sun becomes the ascendant Lord and hence is very auspicious. Sun placed in the Ascendant, 9th house, 5th house and 11th house will bring good benefits if a Ruby is worn. Individuals who are having the placement of Sun as described earlier should wear a Ruby for life. Placement of the Sun in the 3rd and the 6th house should be considered only during major period and sub periods.

Virgo Ascendant
Individuals with Virgo ascendant should never try a Ruby except under he guidance of a competent Astrologer. The Sun here becomes the Lord of the 12th house and the Sign of Exaltation is occurring in the 8th house. Although a Vipareeta Raja Yoga is caused still Ruby should be avoided. Whatever results the Sun has to give due to its exaltation it will give itself. There is no need to increase its power by wearing a Ruby.

Libra Ascendant
Libra Ascendant individuals should first see the position of Saturn and Venus. If these two are not well placed, only then Sun's position be analyzed for the purpose of Gemstone wearing. Also If the Sun's major period (Mahaa-Dashaa) is running then Ruby can be considered. Sun in the 11th House, 2nd House and 7th House can be considered.

Scorpio Ascendant
Sun is an auspicious planet for Scorpio Ascendant. It owns the 10th quadrant of Profession and is the friend of the Ascendant Lord. Individuals whose Sun is placed in the 10th House, or 5th House, or 9th House, or 6th House should wear a Ruby.

Sagittarius Ascendant
Sun becomes a auspicious planet for this auspicious ascendant ruled by Devguru Brihaspati. Individuals who are having the Sun in the 5th House, or 9th House or the ascendant, should wear a Ruby for life. The Sun's placement in 2nd, 3rd, 4th, 7th and 10th Houses should only be considered during Sun period. The Sun's placement in the 6th, 8th and 11th Houses should be avoided completely.

Capricorn Ascendant
The Sun's gemstones should be completely avoided. Firstly it owns the 8th House of losses and accidents and secondly it is the enemy of the Ascendant Lord. The Sun Saturn enmity is legendary. The Sun is best pacified here by giving Arghya or by Soorya Namaskar. The Sun's placement in 4th, 3rd House can be considered for those who have interest in Occult, alternative medicine, Hatha Yoga or Teevra Sadhanas.

Aquarius Ascendant
During the Sun Mahaa-Dashaa Ruby be considered only when Sun is placed in 3rd, 7th, 10th or 11th House. First see the position of Venus.

Pisces Ascendant
Ruby should be considered if Sun is placed in its own sign in the 6th House or in the second house of wealth in exaltation. In rest of the positions it is not necessary to wear a Ruby.

When to wear a Ruby:
Ruby should be worn on a Sunday in Pushya Nakshatra. Other constellations auspicious for wearing a Ruby are Krittikaa, U-Phaalgunee and U-Aashaadhaa. The Ruby should be worn in Gold or copper in the ring finger after Praan Pratishthaa as the Sun line is found on the mount of Sun located just below the ring finger on the palm. If due to some reason these constellations are not available and it is important to wear the Ruby then use any Shukla Paksha Sunday and wear it in the Hora of the Sun.
Caution: Those who wear ruby should not wear a Blue Sapphire, or Diamond, or Gomedh along with it.

Those individuals in whose chart Sun is not well placed and is giving bad results in the Mahaa-Dashaa or the Antar-Dashaa should donate wheat on Sundays, perform Soorya Namaskaar, Chant the Soorya Gaayatri Mantra, Recite sage Agastya's Aaditya Hridya Stotra and give Arghya to the Sun God. This will ensure peace and prosperity.
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Wearable Laal
The potency of a high-quality ruby is such that even an ignorant person living a sinful life and surrounded by deadly enemies is saved by wearing such a gem. Anyone wearing such a naturally effulgent ruby would be freed from diseases caused by any imbalance of the bodily functions.

A ruby, although genuine, should not be worn if it has strong color banding, excessive inclusions within like numerous internal cracks, a sandy appearance, a rough surface, or is dull and lusterless. Anyone using such a flawed ruby, even by ignorance, will suffer from disease, or loss of fortune.