Colourless Gemstones in 18th to 19th Century Portuguese Jewellery

Portuguese jewellery from the 18th to the 19th century is mostly known by the colours offered by the Brazilian coloured gemstones (e.g. orange, yellow and pink topaz, yellowish-green chrysoberyl, blue aquamarine, red almandine garnet, lilac amethyst, yellow citrine). Colourless gemstones were also popular in the period, mostly diamonds, but other gems included as it will be discussed here in detail.

Mid-18th century demi-parure in gold and silver set with rose cut diamonds. Foto Carlos Pombo Monteiro © Arquidiocese de Évora / Fundação Eugénio de Almeida

From a gemmological point of view, the jewellery production of the second half of the 18th century and first quarter of the 19th century in Portugal differ from the European where coloured or colourless pastes, or glass, were rather abundant. High-end pieces all around Europe, and in Portugal for all that matter, were, of course, keen in the use of the most valuable gems of the period, like diamonds, pearls, rubies, emeralds and blue sapphires. On this segment, differences were negligible in terms of the gems that were used. The main difference lies on jewellery artefacts of a lesser value, mostly in silver, where we notice the use of then almost new coloured gemstones.
There was an historical circumstance that influenced Portuguese jewellery. Until 1822, Brazil was a Portuguese colony and even the capital of the Portuguese empire when prince regent João, son of the queen D. Maria I and future king D. João VI, set court in São Salvador, Bahia, and two months later in Rio de Janeiro, the capital, after the Napoleonic invasions of 1807, renaming the nation as the United Kingdom of Portugal, Brazil and the Algarves. This historical close relationship did put Portugal on a privileged position to receive shipments of the gem and also gold production of Brazil. The discovery of gold in the late sixteen hundreds lead to the exploration of the local grounds in the search for the precious metal, which eventually resulted in the discovery of more gold deposits and several gem occurrences, the most important of which was diamond in the early 1720’s. Among the other local gems varieties with significance in the period’s jewellery, the following could be underlined: topaz (colourless, yellow, orange and pink, including the so-called “imperial” colours), quartz (mostly rock-crystal and amethyst), garnet (red coloured almandine-pyrope varieties), chrysoberyl (yellow-green) and beryl (specially aquamarine and near-colourless goshenite type). It is undeniable that these Brazilian gems, so conveniently available in large quantities to Portuguese jewellers, played a fundamental role in Portuguese jewellery leaving a truly typical signature to it, quite different from the European jewellery of the same period, as it has been stated before.

In the present essay, only the colourless gems will be discussed and contextualised in the jewellery designs used in Portugal, as well as the types of setting, foiling and other appearance modification techniques. Note that the variety of colourless materials is not that comprehensive, as in the late David Kent’s FGA collection of colourless stones (published in The Journal of Gemmology (1987), vol. 20, no. 6, pp. 344-345), but is interesting to understand how and why these were used. It is also important to realize that simple gemmological techniques and intermediate observation skills can positively distinguish between these few colourless gems that are, apparently, alike due to their lack of colour.

Diamond

Brazilian diamonds are truly the most important gem in the jewellery of the 18th century, not only in Portugal, but also all around Europe, in consequence of the huge quantities of stones coming from there since the 1720’s, considering the period’s standards. It is not too much to remember that until then, diamonds came essentially from India and from Borneo (in today’s Indonesia) to a lesser extent, serving jewellery makers in Europe and in the Orient. To put this in perspective, on those days when Indian production was at about a few thousands of carats a year, the several tens of thousands of carats a year in some periods of the 18th century meant a significant contribution to the industry, with direct impact in jewellery design, cutting industry, fashion and of course, in demand. Regardless to say that this yearly production would be negligible today, as the world diamond production is measured not in tens of thousands of carats, but in millions of carats (according to official Kimberley Process figures, in 2016 the production was about 144,6 million carats in volume - Brazilian exports were 181.525,69 carats, a mere 0,125% of the world diamond production). But back then, the use of jewellery was only possible to the most powerful and wealthy figures of society (e.g. sovereigns, the aristocracy and high-ranking members of the Church), so the many tens of thousands of carats were enough to satisfy that selected clientele.
Coincidently, almost at the same time some changes were being noticed in the polishing styles for diamond in terms of demand, with an increase in the popularity of the so called triple cuts, known as the brilliant cut. Notwithstanding the fact that this style of cut was already known in the late 17th century, its popularity was only consolidated in the mid 18th century and the then popular few centuries old rose cuts began to decline in demand, specially for larger goods. The use of candle lights to illuminate the lavish ballrooms and salons of the exquisite social events of the period caused a greater visual impact on the brilliant cut when compared with the rose cut. The name of the cut speaks for it self on this matter.

Silver and gold stomacher dated ca. 1758 set with brilliant cut diamonds. Note the dark visual appearence of the culets on each diamond. The red gems include ruby, garnet and topaz. Foto Carlos Pombo Monteiro © Arquidiocese de Évora / Fundação Eugénio de Almeida

On Portuguese jewellery in particular, the impact of a larger diamond availability is seen in the way jewels were designed. Before the great numbers of Brazilian diamonds, these were mostly noble metal art pieces, made by highly skilled goldsmiths with a great deal of handcraft experience in working the metal with only but a few diamonds being set here and there; after, one can verify that the noble metal, mostly silver, serves as a mere stone holder for the stones, being almost impossible to see any metal, pushing the stone setter craft to a higher level of importance in jewellery making. In other words, jewels became a whole gemstone reality. The evolution of this designs and taste is testified by the increasing number of diamonds and the decreasing artistic metal craftsmanship present in a 3 decade period. It is also noticeable that rose cuts are much more abundant in pre mind-18th century pieces that in the later half a century.
Curiously however, although the greater amount of light return offered by the new cutting styles, when compared with the then traditional rose cuts, the settings were closed, sometimes darkened, concealing the pavilion. Stone setting had been traditionally made in such a fashion for centuries (opened settings, sometimes called “à jour”, became fashionable only in the 19th century). The brilliant cuts in closed, sometimes darkened, settings created a visual effect in the cullet, making it black, an effect that was not achieved naturally by the common diamond simulants of the period, specially when set with the traditional reflective foil back. We’ll come back to this further bellow.
All in all, diamonds were indeed extensively used, due to the availability (and to the drop in prices during a limited time frame) and jewellery design was no longer dominated by metal craft but by rather by stones that totally covered the piece. This is particularly visible on the Portuguese Crown Jewels where fine and large stones can be seen decorating the state and military insignia of the period’s Portuguese Royalty, where metal is barely visible only in the settings.


From the Royal Collections, the plaque of the Three Military Orders (1789) set with brilliant cut diamonds , emeralds and rubies, Note that barely no metal is visible. © Palácio Nacional da Ajuda / DGPC

Topaz

Being diamond the most significant colourless gemstone on this context, other gems came into play in the mid 18th to early 19th century jewellery. As said, the abundance of diamonds created a new way of designing jewels with an immense profusion of stones over an almost invisible metal structure and this style was captured by jewellers when using other colourless gemstones.
Before the discovery of the techniques of treating colourless topaz into the popular vibrant blues so fashionable in today’s markets, white topaz was used as it is: colourless. Due to its significant alluvial occurrences and its specific gravity (topaz SG = 3,53, diamond SG = 3,52), topaz might have been collected along with diamonds right after the mid 1720’s. It was not difficult, however, for the experienced dealer and cutter to separate between the two, namely for their different external shapes, luster, abrasion marks and hardness, of course. It was realised that this gem material had jewellery potential as it had been proven in the past elsewhere in central Europe, namely to simulate (not deceivingly) diamonds in silver jewellery.


Early 19th century stomacher in silver, set with colourless and very light pink topaz. © Museu Nacional de Arte Antiga / DGPC


The style of cut of such stones was very close to the so-called double and triple cuts used for diamonds, always with a significant culet size. In the setting, made in the same closed fashion as with diamonds, there is invariably the use of a reflective foil back to enhance the stone’s brilliance. It happens that, in such circumstances, the culet would appear dull or white and that was not the visual aspect that was so popular among consumers due to the visual appearance of set diamonds where the closed settings and darkened back caused the culet to appear black. To achieve that effect with topaz, setters used a subterfuge, painting a black dot in the culet itself creating that same impression. A closer look into non-diamond foil-backed colourless gemstone jewellery artefacts from Portugal in this period shows the presence of black dots in every stone’s cullet. All are painted dots as it can be seen under magnification.

The presence of the black painted culets is easily seen under magnification

Some regional trade names, like “minas novas” and “pingo d’água” were used for topaz on those days, especially in the beginning of the 19th century. Minas Novas is actually a region in Minas Gerais from where white topaz came in significant quantities in the early 19th century. The lack of gemmological knowledge and verbal tradition among traders and consumers led to the indiscriminate use of this trade name for the other two Brazilian colourless gem varieties used in this period: quartz and beryl. This has caused some confusion in the interpretation of the actual gem content of 19th century items, as well as in some 18th century jewels where some dealers still call anachronistically “minas novas” to every non-diamond colourless gem material set in Portuguese jewellery.

Quartz

Almost the same narrative that was made with topaz applies when in comes to rock crystal (colourless quartz), but in this case the quantities are much much larger than with topaz. It was soon understood that the tips of quartz crystals and their eroded aluvial parents were suitable for faceting, much in the same way as European and Asian colourless quartz were in the past for both faceting and carving. Their use in jewellery was barely the same as with topaz, being extensively employed in silver jewellery with closed settings, reflective foil backs and, almost always, with the black painted culets. It is noticeable though that the quality of the pieces using quartz is not as delicate as those using topaz, specially in civil or profane pieces, indicating an interesting rarity factor and a different value perception between both gem varieties, with topaz being more exclusive and expensive. The lesser hardness of quartz (7 in the Mohs scale, compared with 8 for topaz) and its lower reflective properties do make them less brilliant than topaz and, hence, less desirable. The abundance factor also plays a role here of course. The separation, however, is hard to achieve by visual observation alone. Since most of these stones are set in jewellery, the use of the standard refractometer is limited and other simple gemmological techniques must be used to collect diagnostic information. The reaction to ultraviolet light and the thermal properties combined do help in this case.

Late 18th century earrings in silver set with rock crystal. Note the black points at the center of  the  stones, being the culets painted with black. Photo Carlos Pombo Monteiro © Arquidiocese de Évora / Fundação Eugénio de Almeida

Beryl

The last colourless gemstone dealt in this article is not really colourless, but rather a very pale greenish-blue material. Beryl rarely occurs in the true colourless variety, known as goshenite, and almost all the beryls observed in this period’s Portuguese jewellery are, in fact, very pale aquamarines, which can be easily demonstrated using the Chelsea Colour Filter. Like with quartz and topaz, a closed setting is used with a reflective foil in the back, as well as with the so mentioned black dot in the culet to create the desired “diamond dark culet” effect. So visually, at first glance, all these colourless gemstones are alike. A subtle difference, however, between these gems is the face up higher brilliant appearance of beryl and, as with topaz, these were used in finer pieces when compared with rock crystal.
Early 19th century insigna of the Order of Nossa Senhora da Conceição de Vila Viçosa featuring very light greenish-blue aquamarines, almost colourless beryls. Photo Carlos Pombo Monteiro © Arquidiocese de Évora / Fundação Eugénio de Almeida

In conclusion, the exploration of the Brazilian soil in the 18th and 19th centuries lead to the discovery of several gem materials, mostly diamonds, that made a strong impact in the whole concept of jewellery, not only in Portugal, but also in Europe. Being used not much as deceiving diamond simulants, topaz, quartz and beryl also secured a place among the choices of those days’ Portuguese jewellers being used, set and fashioned in a very typical fashion in silver artefacts of a much lower cost that diamond jewellery. Many of those pieces survived due to the lower values associated with both the gems and the metal, as a different fate was met for diamond set and/or gold made pieces for obvious reasons. Several public and private museums have numerous profane and devotional artefacts featuring these Brazilian colourless gemstones that are valuable testimonies of the period’s jewellery production and are the delight for historians, collectors and passionate professionals or consumers. 

Edited and extended from Galopim de Carvalho, Rui (2008), Colourless gems in Portuguese 18th to 19th century Jewellery, Gems & Jewellery News, Vol. 17, no. 1, pp. 25-27



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