Using stones as symbols is as old as writing. The Egyptians ground lapis lazuli for Tutankhamun’s eyelids, the Romans wore amber against the evil eye, and in the Middle Ages lapidaries — treatises listing each stone’s virtues and dangers — circulated in monastic libraries beside the herbals. Pliny’s Naturalis Historia devotes a whole book to gems and the properties ascribed to them.
This encyclopedia sorts the stones into six families — love, protection, energy, healing, spirituality, clarity — because that is how modern crystal healing groups them. For each one you get the chakra and element it is linked to, the stones tradition considers compatible, the ones better left apart, and the recommended way to cleanse it: some dissolve in salt, others fade in sunlight, and it is worth knowing beforehand.
What you read here is symbolic tradition, not medicine: no stone cures an illness and none of this replaces a doctor. One thing does remain true, though — holding a small, cold, heavy object while thinking through a problem genuinely helps you concentrate. The crystal does not do the work for you: it gives your attention something to rest on.