Gemstones occupy a large place in Indian tradition, and a small one in the evidence. Both facts deserve stating.
In Jyotish, the navaratna — the nine gems — correspond to the nine planetary influences: ruby for the sun, pearl for the moon, red coral for Mars, emerald for Mercury, yellow sapphire for Jupiter, diamond for Venus, blue sapphire for Saturn, hessonite for Rahu and cat's eye for Ketu. Stones are prescribed to strengthen a weak planetary position, set in specific metals and worn on specified fingers.
Ratna Shastra and sections of Ayurvedic texts describe gem preparations. Similar traditions exist in China, in the Islamic world, and throughout medieval Europe, where lapidaries listed the virtues of stones at length.
There is no scientific evidence that gemstones affect health, and no proposed mechanism that survives examination. Controlled tests of crystal healing have found that people report the same sensations from convincing fakes as from real stones — which tells you the effect is expectation, not mineral.
I record the tradition because it is a genuine and beautiful part of Indian culture, and because for many people wearing a stone is bound up with faith and with family. That is their business, and I would not mock it. But it should not be relied on to treat illness, and it should never delay proper treatment.
Never make or drink a gem elixir. Malachite, cinnabar, galena, orpiment and several other decorative minerals are seriously toxic — cinnabar is mercury sulphide, galena is lead.
Be careful of cost. Gemstone prescribing is an area where vulnerable and frightened people are routinely charged very large sums. If someone tells you that a stone will cure a serious illness, they are either mistaken or taking advantage of you.
This site is a personal account and a record of traditional practice, shared for information. It is not medical advice, not a diagnosis, and not a treatment for any disease. I am not a doctor.
If you are unwell — and especially if you have a serious illness such as cancer, diabetes or heart disease — please stay under the care of a qualified physician. Nothing here should replace or delay that care.