corundum, history.1, India.12, gems, Indian lapidary

Ratna Pariksha [रत्नपरीक्षा; Gem Testing], composed in 1316 by the Jain scholar and administrator Thakkura Pheru, is a medieval Indian treatise devoted to the identification, classification, evaluation, and valuation of precious stones. Written in Apabhraṃśa, it discusses important gems encountered in the Indian trade, including diamonds, pearls, rubies, sapphires, emeralds, and other precious materials, describing their varieties, desirable and undesirable qualities, defects, weights, and commercial values. The work is particularly important to the history of gemology because Pheru drew upon practical experience with gems, weights, measures, and monetary calculations rather than treating precious stones solely within the religious and astrological traditions characteristic of many earlier Indian lapidaries. It consequently provides valuable evidence for the terminology, testing practices, grading criteria, and economics of the gem trade in early 14th-century India.