Garcia da Orta's Colóquios dos Simples e Drogas da Índia — rendered in English as Colloquies on the Simples and Drugs of India — stands as one of the most consequential scientific texts produced by the Portuguese Estado da Índia. Published in Goa in 1563 by the printer João de Endem, it was the first substantial European work on natural history to be printed in Asia, and among its many subjects it offered the earliest sustained eyewitness account by a European-trained observer of the gemstones circulating through Indian Ocean trade networks. For historians of gemmology, the Colóquios occupies a position analogous to that of Pliny's Naturalis Historia in classical scholarship: it is a primary source of irreplaceable documentary weight, capturing a moment when European knowledge of Asian gem sources was still largely inferential, and replacing inference with direct observation.

Garcia da Orta: Physician, Naturalist, and Witness

Garcia da Orta was born around 1501 in Castelo de Vide, in the Alentejo region of Portugal, to a family of converso (Jewish-convert) origin. He studied medicine at the universities of Salamanca and Alcalá de Henares before returning to Lisbon, where he lectured at the university and practised medicine. In 1534 he sailed for India in the fleet of Martim Afonso de Sousa, a departure that would prove permanent: da Orta spent the remainder of his life in Goa, serving as physician to successive governors of Portuguese India and accumulating, over nearly three decades, an unparalleled body of direct knowledge about Asian materia medica, spices, and natural products — including gemstones.

His position in Goa placed him at the centre of one of the sixteenth century's most dynamic commercial entrepôts. Goa was the administrative capital of the Estado da Índia and a hub through which goods from the Malabar Coast, the Deccan sultanates, Ceylon, Burma, Persia, and the Red Sea littoral converged. Merchants, factors, physicians, and rulers passed through or corresponded with the city. Da Orta's social and professional connections gave him access to gem specimens, to traders who could speak to provenance, and to the rulers and courts that consumed fine stones. When he finally committed his observations to print in 1563 — the year before his death — he was drawing on a lifetime of situated, empirical enquiry rather than on the recycled classical authorities that dominated European lapidary literature of the period.

Structure and Method of the Colóquios

The Colóquios is organised as a series of dialogues — a literary device common to Renaissance scientific writing — between da Orta himself and a fictitious interlocutor named Ruano, a recently arrived Portuguese physician who poses questions that allow da Orta to expound on each subject. The format is conversational and occasionally digressive, but the underlying method is empirical: da Orta repeatedly appeals to personal observation, to specimens he has handled, and to testimony from traders and rulers he has met, explicitly contrasting this evidence with the errors he finds in Dioscorides, Avicenna, and other received authorities.

The work covers some sixty colloquies on drugs, spices, and natural substances. Gemstones appear principally in the colloquies devoted to diamonds, rubies, and pearls, though incidental references to other stones — including bezoar stones, which occupied an ambiguous position between mineral and medicinal object — are scattered throughout. The gem colloquies are notable for their attention to geography, to the social contexts of gem use, and to the mechanics of trade, as well as to the physical properties of the stones themselves.

Diamonds: Challenging Classical Authority

Da Orta's treatment of diamonds is particularly significant because it directly contradicts several long-standing European misconceptions. Classical and medieval lapidary literature had located diamond sources vaguely in Arabia or in the mountains of India, and had perpetuated the myth that diamonds could be softened or broken only by goat's blood. Da Orta dismisses the blood myth explicitly, noting that he has never encountered any evidence for it among the merchants and miners with whom he spoke, and that the stones he examined showed no such susceptibility.

More importantly, he provides specific geographical information about Indian diamond sources, identifying the mines of the Deccan region — the territories controlled by the Vijayanagara Empire and the Deccan sultanates — as the principal origin of the diamonds reaching Goa. He describes the alluvial and pipe-like deposits in terms that, while not using modern geological vocabulary, accurately reflect the character of the Golconda-region mines that would later become famous as the source of the Koh-i-Noor, the Hope Diamond, and other historic stones. His account of the grading and valuation practices used by Indian merchants, including the use of weight-based pricing and the recognition of colour and clarity as value determinants, anticipates the systematic grading frameworks that European traders would only begin to formalise in the following century.

Rubies: Burma and Ceylon Distinguished

The colloquy on rubies is among the most gemmologically precise sections of the work. Da Orta distinguishes between rubies from Burma — which he associates with the kingdom of Pegu, the Mon kingdom whose capital controlled the overland trade routes from the Mogok region — and those from Ceylon (present-day Sri Lanka). He notes that the Pegu stones were generally regarded as superior in colour, a judgement consistent with the later European and Indian preference for Burmese rubies and with the modern understanding that Burmese rubies from Mogok can achieve the deeply saturated, fluorescent red known in the trade as pigeon's blood. The Ceylonese stones he describes as tending toward a lighter, more pinkish tone — again consistent with the characteristic appearance of Sri Lankan corundum, which typically contains less iron and exhibits stronger fluorescence but lighter saturation than Mogok material.

Da Orta also records the commercial routes by which Burmese rubies reached Goa: overland through the Deccan, or by sea through the ports of the Coromandel Coast. His account of the pricing of rubies — including the observation that very large, fine rubies commanded prices exceeding those of diamonds of comparable weight — reflects a market reality that persisted well into the seventeenth century and that is documented in later sources including Jean-Baptiste Tavernier's Les Six Voyages (1676).

He also touches on the practice of heat treatment, noting that some stones were subjected to fire to improve their appearance, though his description is brief and does not distinguish clearly between the deliberate enhancement of colour and the accidental effects of heat. This passing reference is nonetheless among the earliest European documentary notices of what would later be understood as thermal treatment of corundum.

Pearls: The Persian Gulf and Indian Ocean Fisheries

Da Orta's colloquy on pearls draws on his knowledge of the Persian Gulf fisheries — centred on Bahrain and the Trucial Coast — and of the Gulf of Mannar fisheries between Ceylon and the Indian subcontinent. He describes the seasonal character of the pearl harvest, the diving practices, and the role of Arab and Indian merchants as intermediaries between the fishing communities and the courts of India and Portugal. His account of pearl valuation, including the premium placed on roundness, lustre, and freedom from blemish, is consistent with the criteria documented in later Indo-Persian gem treatises and in European merchant correspondence of the period.

He is also attentive to the medicinal uses of pearls, which in sixteenth-century pharmacopoeia were dissolved in acid preparations and administered for a range of conditions. This dual status of pearls — as luxury ornament and as materia medica — is a recurring theme in the Colóquios and reflects the broader context of the work, which is primarily a pharmacological text rather than a lapidary in the strict sense.

Significance for the History of Gemmology

The Colóquios occupies a pivotal position in the intellectual history of gem knowledge for several reasons. First, it represents the point at which European understanding of Asian gem sources began to be grounded in direct observation rather than in classical inheritance or travellers' hearsay. Earlier European texts — including Marco Polo's Divisament dou Monde and the various medieval lapidaries — contained information about Asian gems, but that information was filtered through multiple layers of transmission and was rarely subjected to critical scrutiny. Da Orta, by contrast, was a trained natural philosopher who applied the empirical methods of Renaissance medicine to the study of gems, explicitly testing received claims against his own experience.

Second, the Colóquios documents a specific historical moment in gem commerce: the period immediately following the Portuguese establishment of direct sea routes between Europe and Asia, when the traditional overland and Red Sea trade networks were being disrupted and reorganised. Da Orta's account of the gem trade reflects this transitional moment, capturing the persistence of older Levantine and Arab trading networks alongside the new Portuguese maritime system.

Third, the work had significant influence on subsequent European natural history. It was translated into Latin by Carolus Clusius (Charles de l'Écluse) in 1567 as Aromatum et Simplicium aliquot Medicamentorum apud Indos Nascentium Historia, a translation that made da Orta's observations accessible to the broader European scholarly community and that was reprinted multiple times over the following decades. Clusius's edition introduced da Orta's gem observations to readers who would not have had access to the Portuguese original, and it influenced subsequent natural historians including Conrad Gessner and, indirectly, the compilers of the great seventeenth-century gem treatises.

Limitations and Context

The Colóquios must be read with an awareness of its limitations. Da Orta was a physician, not a mineralogist, and his descriptions of gem properties are those of an educated observer rather than a trained gemmologist. He does not systematically distinguish between varieties of corundum, and his use of colour terms reflects the vocabulary of his time rather than any precise chromatic standard. His geographical information, while often accurate, is sometimes vague or conflated — he does not always distinguish clearly between different mining localities within a region, and his understanding of the geological processes that produce gem deposits is, inevitably, pre-scientific.

There is also the question of his sources. While da Orta emphasises personal observation, much of his information about gem sources he had not himself visited — Burma, in particular — was necessarily derived from the testimony of merchants and intermediaries. The reliability of that testimony varied, and da Orta was not always in a position to verify it.

Finally, the Colóquios was published under the shadow of the Inquisition, which had been established in Goa in 1560, three years before the book appeared. Da Orta's converso background made him vulnerable, and it has been suggested by scholars that some of the circumspection in his text reflects the need for caution in a hostile intellectual environment. He died in 1568; his sister was burned in effigy by the Inquisition in 1580, and his own remains were reportedly exhumed and burned posthumously — a reminder of the personal risks that attended intellectual life in the Estado da Índia.

Legacy and Availability

The original 1563 Goa edition of the Colóquios is among the rarest printed books in the history of science; fewer than a handful of copies are known to survive, held in major institutional libraries. The Clusius Latin translation of 1567 is more widely held. The standard modern English translation, by Sir Clements Markham, was published by the Hakluyt Society in 1913 as Colloquies on the Simples and Drugs of India, and remains the principal access point for English-language readers. Scholars of the history of science, of Portuguese imperial history, and of the Indian Ocean world have returned to the Colóquios repeatedly as a primary source of exceptional density and reliability for the mid-sixteenth century.

For the gemmologist and gem historian, the work's value lies not in any systematic treatment of mineralogy — which it does not attempt — but in its documentary record of how gems were perceived, valued, traded, and understood at a moment when the global gem trade was being fundamentally reorganised by European maritime expansion. In that sense, the Colóquios is less a lapidary than a portrait of a world in which gems were embedded in networks of commerce, medicine, power, and knowledge that da Orta observed with unusual acuity and recorded with unusual honesty.

Further Reading

• GIA Gems & Gemology — Historical Gem Trade Research
• Hakluyt Society — publisher of the Markham English translation (1913)