Gemology was known as ratna shastra and ratnas in ancient Hinduism. Ratnas (gems) have always had a significant place in Hindu values and beliefs. Around the 6th century CE nine gems were clearly identified for their protogical association with the navagrahas (nine planets). They are manikya (ruby) – sun; mukta (pearl) – moon; vidruma (coral) – mars; marakata (emerald) – mercury; indranila (sapphire) – Saturn; vajra (diamond) – Venus; pushparaga (topaz) – Jupiter, gomeda (zircon) – Rahu and vaidurya (cat’s eye) –Ketu. To ensure harmonious relationship with the planets so as to seek their beneficial effects, the prescribed positioning of gems in a suitable gold setting is as follows:
Agastya Samhita, an early text, has dealt with the association of gemstones with weekdays as well as the order in which gemstones are to be placed on an elevated platform for worship.
Arthashastra of Kautilya, of the 4th century BC, provides a succinct description of the important gems and jewels. The Sanskrit work Kadambari of Banabhatta (6th century CE) mentions ratna shastra as one of the subjects taught to princes. Varahamihira of the 5th century CE in his encyclopedic treatise Brihat Samhita (80.4-5), identifies as many as twenty two different varieties of gems, but the most important are navratnas (nine gems) – diamond (vajra), pearl (mukta), ruby (manikya), emerald (marakata), sapphire (indranila), coral (vidruma), cats-eye (vaidurya), topaz (pushparaga) and gomeda (zircon).
The science of precious stones, ratna shastra, developed as an independent discipline in India.
In chapters 80-82 of the Brihat Samhita of Varahamihira (early 6th century CE) one finds a succinct account of Hindu gemology. This text accords a pride of place to the diamond and ever since, it has been the diamond that has won recognition as the king of gems. Varahamihira describes 23 types of gems, including their places of origin. Since he was an astrologer-cum-astronomer, he sought to relate some gems with the planets and even deities. It was a common practice at that time to propitiate deities with pancharatna (five gems), comprising diamond, ruby, pearl, emerald and sapphire.
Hindu gemology occupied a distinct position in various societal segments by the 10th century CE. Garuda Mahapurna, a Puranic text probably belonging to this period, has devoted twelve chapters to the origin, distribution, typology as well as good and malefic characteristics of several gems. It also throws light on how to distinguish between genuine and artificial ones, as well as the divinities overlording the main gemstones, with some astrological aspects. As for the origin of diamonds and other gems, this Purana subscribes to a mythical idea found in an earlier text, Agastya Samhita, that they originated from the organs of a demon called Vala. These strange ideas continued to appeal to common people, despite a scientific appraisal of the origin of gemstones by Kautilya and Varahamihira.
The merit of Garuda Mahapuran lies in the fact that it describes a scientifically significant method of boring pearls and cleaning them to enhance their luster. It further describes five varieties of artificial rubies and stresses that weight (specific gravity) should be the main criterion for identifying the genuine from the artificial ones. More importantly, it asserts that a diamond can be scratched only by another diamond, pointing to, in modern parlance, Mohs scale of hardness. That sapphires are associated with rubies, as stated in this Purana, is scientifically true from the point of view of modern mineralogy. Likewise, its statement that the coral is obtained from the Kerala coast is equally valid even today.
The Roman historian Pliny (1st century CE),in his Historic Naturalis, has spoken of Indian adams (diamonds), smaragdus (emeralds) and a few other precious stones and minerals. The 2nd century Greco-Roman Ptolemy has mentioned the mining of diamonds in India. There was a huge treasure of diamonds and other gems.
The exquisite art of diamond lapidary is very old in India. Agastya Samhita has given an account of effective and functional tools of diamond cutting. Indian lapidary is a living tradition and over a million artisans engaged in this industry are well known globally for their artistic craftsmanship. Diamond merchants world over prefer the raw diamonds cut by Indian craftsman, although diamond production in India is much lower than in countries like South Africa.
While full-fledged treatises like Rantapariksha by Buddhabhatta and Rayana-parikha and Agastimala are available for print, the subject has been treated in detail also in several encyclopedic treatises like Brihat Samhita of Varahamihira (hs.8-83), Manasollasa of Someshvara (II.4,4.2 – 536), and Shiva Tattva Ratnakara of Basava of Kaldi (VI and XVII).
The topics dealt with in these texts on gemology are comprehensive and include the sources of the gems, their provenance, varieties, qualities, flaws, specific gravity, hardness and the like. Interestingly, an idea of their prices is also indicated.
The Mineral Wealth of India (1956) A.D.Dey and C.J.Brown – Oxford University Press, Mumbai
Encyclopedia of Hinduism Volume IV page 269-270 - IHRF