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" The second group of beliefs, those relating to the generation of ores and stones in the belly of the earth - deserve particular attention. Rock engenders precious stones. The Sanskrit name for Emerald is, acmagarbhaja, 'born from rock', and the Indian minerological treatises describe its presence in the rock as being in its 'matrix'. The author of the Jawaher nameh (The Book of Precious Stones) distinguishes diamond from crystal by a difference in age expressed in embryological terms: the diamond is pakka, i.e. 'ripe', while the crystal is kaccha, 'not ripe' , 'green' , insufficiently developed. "
― Mircea Eliade , The Forge and the Crucible: The Origins and Structure of Alchemy