Gem testing did not begin with the refractometer. India was the world's principal source of diamonds until the eighteenth century, a centre of the ruby, sapphire and pearl trades for far longer, and — because valuable stones attract imitation — a place where the problem of telling genuine from false was taken seriously early. The modern laboratory stands on that history.
The classical texts
The Arthashastra, attributed to Kautilya and compiled around the fourth century BCE to the second century CE, describes the duties of the superintendent of the treasury, including the examination of gems, pearls and coral by their colour, form, weight, lustre and defects, and names sources and qualities. It is a bureaucrat's manual, and its concern with detecting inferior and substituted material is recognisably a testing concern.
The ratnashastra or ratnapariksha literature — texts on the examination of gems — developed over the following centuries. The Ratnapariksha of Buddhabhatta (around the sixth century), the Agastimata, the Navaratnapariksha, and gem chapters in the Brihat Samhita of Varahamihira (sixth century) and the Garuda Purana describe the nine gems and others, their sources, their defects (dosha) and virtues (guna), and methods of examination: colour under different lights, hardness by scratching with other stones, lustre, transparency, the "feel" of the stone, and the identification of glass and other imitations by their lightness and lack of fire.
These texts already distinguish natural stones from imitations (kritrima), grade stones by quality, and connect them to astrology — the Navratna tradition is fully formed in them. The Navratna: nine gems and their substitutes.
The medieval and Mughal trade
Under the Delhi Sultanate and the Mughals, Indian gem markets — Golconda for diamonds, the ports for pearls and coral, Jaipur and Surat for cutting — were the largest in the world. Court jewellers and the jauhari (gem dealers) developed practical expertise transmitted by apprenticeship: identifying stones by eye, by weight in the hand, by the ratti balance, by the scratch plate and by the loupe. Treatments — oiling emerald, heating corundum — were known, and so were the means of detecting them, within the limits of the eye.
European travellers such as Jean-Baptiste Tavernier (seventeenth century) recorded the trade in detail, including the careful examination of stones before purchase and the prevalence of imitations.
The scientific instruments
The nineteenth century brought the instruments that define modern gemmology: the refractometer (Herbert Smith's gem refractometer of 1907 building on earlier designs), the spectroscope (applied to gems from the 1860s), specific gravity by hydrostatic weighing (ancient in principle, precise with modern balances), and — decisively — the microscope, which after Verneuil's synthetic ruby of 1902 became the tool for separating natural from synthetic by inclusions. The polariscope, dichroscope and UV lamp followed.
Gemmological education arrived in India in the twentieth century, through the Gemmological Association of Great Britain's qualification and later through Indian institutions in Jaipur, Mumbai and elsewhere. Testing laboratories were established to serve the export trade, and their reports became a normal part of a stone's documentation.
Rudraksha testing
The examination of Rudraksha stayed within tradition and trade practice for much longer. Texts distinguished Rudraksha from Bhadraksha and warned against false beads; dealers judged beads by eye and by the folk tests — water, copper coin — that are still repeated. Systematic laboratory examination, with magnification and X-ray radiography to count internal compartments, is a recent development, and its adoption has been driven by the same force that drove gemstone testing: the rise in value of rare beads and the corresponding rise in carved and assembled fakes. How X-ray testing of Rudraksha works.
What the modern laboratory inherits
From the classical texts: the categories — the nine gems, their substitutes, genuine and imitation, defect and virtue — and the principle that a stone should be examined before it is trusted. From the trade: the practical eye, the ratti and the loupe. From science: instruments that measure what the eye can only estimate. And from the last century: the report — a written, numbered, verifiable record that outlives the transaction. Why laboratory certification matters.
Frequently asked questions
Did ancient Indian texts describe fake gems?
Yes. The ratnashastra literature warns of glass and other imitations and gives tests — lightness, lack of lustre, softness — to detect them.
Were gems treated in classical times?
Oiling of emerald and heating of some stones are old practices; the texts and later trade accounts refer to enhancement and to the detection of it.
When did Indian laboratories begin issuing reports?
Formal gemmological reports became common in the second half of the twentieth century with the growth of the export trade and gemmological education.
Is the ratti in the old texts the same as today's?
No. The ratti was a seed weight and varied by region and period; the modern standardised value is a convention. Ratti, carat and gram.
Does the tradition conflict with modern testing?
The tradition's concern — that a stone or bead be genuine and of true quality — is exactly what modern testing serves. The instruments are new; the purpose is old.