Gemstones: Which Stone for Which Planet, on Which Finger, and When Not to Wear One

The use of gems in astrology is very old. Each planet has a principal gem, held to strengthen that planet when worn. Here lies the most common mistake: a gem does not make a planet "good", it makes it "strong". If a planet rules a harmful house in your chart, its gem can strengthen the harm too.

The nine gems

Planet	Main gem	Substitutes	Metal	Finger	Weekday
Sun	ruby	red garnet	gold or copper	ring finger	Sunday
Moon	pearl	moonstone	silver	little finger	Monday
Mars	red coral	carnelian	gold or copper	ring finger	Tuesday
Mercury	emerald	peridot, green tourmaline	gold	little finger	Wednesday
Jupiter	yellow sapphire	citrine	gold	index finger	Thursday
Venus	diamond	white sapphire, zircon	silver or platinum	middle or little finger	Friday
Saturn	blue sapphire	amethyst	silver or panchadhatu	middle finger	Saturday
Rahu	hessonite (gomed)	—	silver or panchadhatu	middle finger	Saturday
Ketu	cat's eye	—	silver or panchadhatu	little or middle finger	Tuesday or Thursday

Almanacs and lineages differ slightly on fingers, metals and days. The right hand (the working hand) is usual.

The real rules for choosing

Prescribing by moon sign ("coral for Aries") is the most common and least complete method. An experienced astrologer looks at:

House rulership from the lagna: the lagna lord and the lords of the fifth and ninth are usually safe and helpful; gems of the sixth, eighth and twelfth lords are usually avoided.
Weakness: a gem makes sense when a helpful planet is weak and needs strengthening.
The running dasha: the dasha lord's gem is often suggested, if that planet is helpful.
Planetary friendship: gems of enemy planets are generally not worn together (ruby with blue sapphire, or pearl with diamond).

Cautions about blue sapphire, hessonite and cat's eye

The gems of Saturn, Rahu and Ketu are believed to act fastest and most powerfully, so custom is stricter about them. Before wearing blue sapphire it is traditional to keep or wear it on trial for a few days, and to remove it at once if bad dreams, accidents or unease follow. Wearing a blue sapphire just because "sade sati is running", without looking at the chart, is unwise.

When buying

Weight: a common rule is one ratti per ten units of body weight, though an astrologer may say more or less after seeing the chart. One ratti is taken as about 0.91 carat (0.9 to 0.91 by different reckonings).
Natural or synthetic: astrology speaks of natural gems. Lab-made stones, glass, dyed and heat- or glass-filled stones are all sold. Ask for a certificate from a recognised gemmological laboratory.
Flaws: the old texts forbid wearing cracked, spotted or internally flawed gems.
Consecration: by custom a gem is put on at an auspicious time on its weekday, with the planet's mantra.

A last word

Gems can support; they are not miracle cures. For serious problems of health, law or money see a doctor, lawyer or specialist; a gem cannot take their place. Before buying an expensive stone, have your chart checked. Suvolagna offers personal consultations.

Common questions

What is Jupiter's gem?

Yellow sapphire, usually set in gold and worn on the index finger on a Thursday. Citrine is the common substitute.

Is it right to choose a gem by moon sign?

Not entirely. The gem should follow which planets are helpful from the lagna, which are weak, and the running dasha.

Can anyone wear blue sapphire?

No. It is Saturn's gem and believed to act very strongly. Wear it only after the chart has been checked and, by custom, after a trial.