Artificial Gems

17th century girandole pendant.

In the fifth part of Neri's book, he teaches the secrets of making artificial gems "of so much grace, and beauty, that they will surpass the natural stones in everything except hardness." It is not a difficult argument to make that this section alone is responsible for much of the lasting popularity of L'Arte Vetraria. It is easy to see why enterprising artisans would want to make glass imitations that could pass for the real thing. It is also perhaps too tempting to jump to the conclusion that Neri intended his recipes to be used in deception, since there is no evidence whatsoever that this was the case.

Neri gives full credit for his innovative methods in paste gems to Dutch alchemist Isaac Hollandus. Hollandus is an enigmatic figure, whose writings survive, but not much is known of the man, his family, or even if he was living in Neri's time. What is known is that Antonio's dear friend Emmanuel Ximenes was the brother-in-law to Baron Simon Rodriguez d'Evora, a famous diamond dealer and jeweler of choice to royalty throughout Europe. He lived and worked on the same street in Antwerp as Ximenes' palace, only a few steps away from Neri's new temporary home. It was a common request of wealthy patrons to have duplicate jewelry made in paste for travel and security reasons. If a fake necklace or jewel could pass for the real thing, it was well worth the added expense, when the genuine article could remain safe under lock and key.

No artificial gem recipes have ever been found among Hollandus' writings, excepting one for ruby which is then crushed up as part of a prescription for the philosopher's stone. It is quite possible that Neri was applying a more general technique from the Dutchman. The basic material for all of Neri's paste gems is a fine lead crystal. The crux of his innovation lay in the form of lead used. Normally, metallic lead sheet was cut into small pieces, and roasted in a kiln such that it would oxidize into powder, but not melt. The powder was then added to the glass melt. In Neri's method the lead was chemically converted into a water-soluble form, which could then be filtered and purified to a much greater extent. The end result was a far better grade of crystal.

In 1697, Jean Haudicquer de Blancourt translated into French and greatly expanded Christopher Merrett's English edition of Neri. Blancourt gave no credit to the Italian for his work, and two years later, when it was translated back into English by Daniel Brown, the connection to Neri was completely lost, but the credit for paste gems remained with Hollandus. In the eighteenth and nineteenth centuries, numerous general encyclopedias of art and craft were published and the so-called 'Hollandus' paste gem recipes turned up many times. Meanwhile, a properly credited French version of L'Arte Vetraria was completed by Holbach in 1752. This edition was more suited to a scientific audience; he faithfully translated the Italian, but also incorporated the full comments of Merrett as well as those of Kunckel who issued his famous German version of Neri in 1679.

True Colors

The European Roller [Pica Marina]

Neri's book, L'Arte Vetraria, is devoted to making glass from raw ingredients found in nature. Many of his finished creations were intended to also resemble the natural world. A number of colors are meant to mimic the appearance of gems and minerals, others are named after plants and animals. Some are easily recognized today, even if they are not as familiar as they were in the seventeenth century.

One of his recipes will make "a wonderful pimpernel green," while others evoke peach and orange blossoms. An entire section of the book is focused on paints that are named after the flowers from which the colors are extracted. Many of these plants have remained common: poppies, irises, violets, lilies, carnations and red roses. Others are less so: the mallow, pomegranate, broom and borage flowers.

In addition to flora, the fauna make a few notable appearances in Neri's book. In chapter 16, in the preparation of iron oxide pigments, he advises that after fifteen days in the furnace, the product will be finished when it takes on the purple color of the peacock. In chapter 73 he gives a method for "tinting rock crystal the color of a viper" and chapter 121 is the method for a glass which is "red like blood."

Named in several chapters is a shade of 'celestial blue,' which Neri likens to the color of the "gazzera marina." Common bird names pose a special challenge for translation in that they, like the birds themselves, never seem to settle in space or time for very long. Vernacular names of a species can change from one century to the next, one region to another, even between adjacent valleys and several species can share the same name. It is with this admonition that we attempt to flush out the elusive gazzera marina.

Consulting a modern Italian dictionary draws the eye to the similar sounding 'gazza marina' (alca torda), known in English as the razorbill. This sea bird inhabits coastal cliffs, but alas, as a close relative of the penguin, it dons only black and white formal attire. Digging deeper we find poet Gabriele d'Annunzio, "At Dawn" carefully tracking the gazzera marina across a salty marsh, in his Halcyon. This time the poet himself throws us off the trail with his description, since no bird sports five digits but the chicken. Turning to etymology, we find another potential match in the magpie (pica pica); it is a credible but unconvincing fit with its blue and white plumage.

Aldrovandi's pica marina

Combing the references of Neri's own sixteenth century, we find the best candidate is the roller (pica marina). This bird was described by naturalist Ulisse Aldrovandi, a friend of Don Antonio de' Medici's father and guest at the Casino di San Marco. Other contemporary authors list the gazzera marina as a synonym to Aldrovandi's pica marina. Neri's Latin translator Frisius (1668) and his German translator Geissler (1678) agreed, both sighting the "Pica Marina" in their works.

Mother Dianora

Agnolo di Cosimo 'Bronzino',
"Portrait of Florentine Noblewoman"
(subject unknown , circa. 1540).

Antonio Neri's mother, Dianora Parenti, was the oldest of six children: three girls and three boys. She was born in Florence, on 11 February 1552, with the given name of Dora listed in the city's baptistery register. In all probability by the age of eighteen she was quite accustomed to helping her mother with the other children; Caterina, the youngest, was born less than a year before Dianora's wedding.

Her father and grandfather were prominent lawyers; together they handled much of the personal business of famed artist Michelangelo. On the 20th day of August 1570, Francesco Parenti walked his eldest child down the aisle to be joined, in holy matrimony, to physician Neri Neri. Two years later, their first child Lessandra was born. 

Historians Luigi Zecchin and Enzo Settesoldi identified four of Antonio's brothers, two older and two younger. They were Jacopo (1573), Francesco (1575), a second Jacopo (1577) and Vincenzio (1579). In addition to these five boys, there were at least two more brothers born later, Emilio (1583) and Alessandro (1587). And there were at least three girls, the first-born child Lessandra (1572) and two younger sisters: Maria (1581) and Lucretia (1584). 

In all, there were ten births by Dianora recorded in Florence, occurring almost like clockwork on a fifteen-month schedule. As did many women of the period, she spent a significant portion of her adult life pregnant. In her case, it was a span of sixteen years, carrying one child after another with minimal interruption.

The birth of a child in Renaissance Florence was no small occasion. Patrician families went to considerable expense on decorations, on food and drink for guests and on gifts for the mother and godparents. "The woman who gave birth, like a bride at her wedding, occupied for a passing moment a position of unparalleled honor,"* more than that, while a wedding signaled the transition from daughter to wife, the birth celebration was a rare social recognition of a woman as an individual.

A genealogical record of the eighteenth century, held at the State Archives in Florence (ASF), confirms most of the Neri children's births. It also sets the date of death for their mother Dianora at 1594 when she would have been forty-two years old. This means Antonio lost his mother when he was eighteen and his youngest brother Alessandro was a mere seven.

* Margaret L. King, Women of the Renaissance (Chicago: University of Chicago Press, 1991), p. 4.

Sonnet to a Barber

Possible portrait of Lodovico Domenichi

In November of 1554, poet Lodovico Domenichi wrote a sonnet to his friend, Jacopo Neri. Jacopo was a barber-surgeon from Dicomano in the upper Arno River valley, then living in Florence. Later he would become grandfather to Antonio Neri. Domenichi was serving a sentence of house arrest in a wretched paper mill in Pescia, in the hills north of Florence. He had been found guilty by the inquisition on charges of translating the heretical writing of John Calvin into vernacular Italian, a crime for which the poet could have easily been executed. Luckily, he had friends in high places and after some nervous time spent in the stockade in Pisa, his sentence was reduced and later commuted by Grand Duke Cosimo I de' Medici.


Jacopo Neri had taken ill with a grave infirmity and when word reached Domenichi, he took pen to paper and composed seventy stanzas in the style of Petrarch. In so doing he bestowed a precious gift, the only one he could under the circumstances; he immortalized his good friend on paper. The sonnet starts:

As I have now come to understand your 
Perilous illness and health,
It is both grief and fondness that I show.  

So may merciful God help you,
Without delay, lest this vile world lose
So much goodness in you, so much virtue.

He goes on to extol Jacopo's kindness towards patients, his willingness to forgive and his admiration among scholars. Along the way, Domenichi describes his own predicament; the cruelties of the mill workers, the muddy floors, his desire to flee and trying to sleep on a bed of frozen straw among the work animals. The rain has been falling for weeks and he is miserable. Recalling happier times he evokes the memories of many mutual friends, including a dwarf named Don Gabriello Franceschi, who delivered sermons at the Cestello church, Neri's family church. Franceschi was from the family into which Jacopo's daughter, Faustina, would later marry. 

There he is called Don Gabriello

Franceschi and I am honored, for good reason,

A giant of men in a small handsome package.

He goes on to describe his saviors; the men who intervened with the Church on his behalf. One was Pompeo della Barba, educated at Pisa and later called to Rome as the personal physician to Pope Pius IV. In the end, Domenichi was pardoned, allowed to leave the damp mill and return to Florence. Within a short time, he was appointed court historian to Cosimo I. Over his career, he published many volumes; translations of works ranging from Xenophon, to Plutarch, to Pliny's Natural History, to a groundbreaking compilation of poems by contemporary women. At the end of his life, Domenichi suffered devastating debilitation, maybe from a stroke, which robbed him of the ability to speak. Even so, he still received regular visits from his old friend Jacopo Neri the barber surgeon. As we turn away from the subject of Lodovico Domenichi, it is hard to resist speculating that a decade after his death, the poet was remembered with fondness by the Neri family in the christening of our glassmaker, whose full name is Antonio Lodovico Neri.

Lodovico Domenichi, "A Mastro Jacopo di Neri, Cerusico, E Barbiere." in Il Secondo libro dell' Opere Burlesche, di M. Francesco Berni.  (Fiorenza: Apresso li Heredi di Bernardo Giunti, 1555), vv. 2. Reprinted many times.

Dear Friends

The library of the University of Leiden (1610)

Christophe Plantin worked here from 1583 to 1585.

One day in July of 1601, in Florence, early in the morning, we imagine two men shaking hands, embracing and saying goodbye. Both knew it might well be the last time they saw each other. The older man climbs into a coach bound for his home in distant Antwerp and signals the driver to begin his journey. That man, Emmanuel Ximenes, had been in Florence to visit his sister, Beatrice, his brother, Niccolò, and several other relatives living in the area. Antonio Neri first met the wealthy banker at the home of Beatrice and her husband, Alamanno Bartolini. The priest lived there after his ordination and, according to nineteenth century historian Francesco Inghirami, functioned as house-master. Both men wished for more time together; they shared a fascination with alchemy and with the work of Swiss-born physician Paracelsus. They had become fast friends and formed a bond that would last until the end of their lives.

As soon as Ximenes arrived home in Flanders he wrote to Neri, on 17 August, 1601, "to the quite magnificent clergyman Mr.Antonio Neri, in the house of Mr. Alamanno Bartolini, in Florence, or where found." He expressed his great pleasure at receiving a booklet of recipes from Neri and declares him "molto caro" [most dear]. He goes on to warn his friend: "With your permission, I will not fail to bother you with my tiresome letters." Over the next two years, the men corresponded frequently. A set of twenty-seven letters written by Ximenes and one by his brother Eduardo, addressed to Neri, survive in the National Library of Florence. The two men discuss a wide variety of subjects including herbal remedies, glassmaking, enameling and in more careful language, the topic for which they were both most passionate: alchemy. They trade information on the results of their experiments and by 5 December, 1602, the banker wrote:

I have seen the tender affection which Your Lordship shows me and demonstrates with the hope to see me before death, which is no different from my own hope. I have desired this from the start… because if we were together, we could easily set to work on some small projects, being that our talents, if I am not deceiving myself, are very well suited...

Neri would ultimately make the journey to Antwerp, but not for another year. That winter he became quite ill in Pisa, postponing his planned visit. Finally, on 2 May, his friend wrote: "Praise God that your indisposition has ended." By the following spring the two men were reunited and Neri would spend the next seven years in a city that was in the eye of a storm. The low-countries (what today is the Netherlands and Belgium) were in the midst of a bloody civil war. The port of Antwerp was blockaded by the Dutch fleet and the countryside was being ravaged by troops from Spain and the Holy Roman Empire. The population of Antwerp was a shadow of its former self, but the city was left untouched by both sides, in an accord of political convenience. It had been burned and pillaged as recently as the 1570's, but by the early 1600's Antwerp was simply too valuable a jewel to be sacrificed.

Emmanuel's immediate family was among the wealthiest in Antwerp and strong patrons of the arts. He counted among his close friends humanist printers Christophe Plantin and Jan Moretus. Other branches of the Ximenes family topped the social ranks in Venice, Hamburg, Lisbon and Florence. Their ancient ancestors were kings of Pamplona, Navarre, Castile and Aragon. Emmanuel's father Rodrigo headed the prestigious Ximenes (Jiménez) Bank in Antwerp. By the end of his visit, Neri would present the prince of Orange with vessels of his chalcedony glass.

Flexible Glass

Tiberius, Third Roman Emperor
(42 BCE - 37 CE)

In the introduction to L'Arte Vetraria, Neri relates the legend of flexible glass. First century historian Pliny and others had already recorded their versions for posterity. Neri writes:

Still others hold that in the time of the Roman Emperor Tiberius, a way of making glass malleable was invented; a thing that was subsequently lost and today is hidden to all. Indeed if such a thing were to be known today, without any doubt it would be more valued than silver or gold for its beauty and incorruptibility, since glass does not give rise to rust or taste or smell or any other adverse quality. 

In Pliny's telling, the hapless artisan was executed on the spot. His workshop was destroyed to prevent the devaluation of the emperor's copper, silver and gold. Consider that this story emerges coincident with the technical development of glassblowing. For the first time in history, artisans could form cups, plates and a variety of glass vessels directly with an iron blowpipe, quickly and inexpensively. Now, glass was available to the masses at affordable prices. The innovation represented nothing short of a revolution in technology. From turning bubbles of glass into vessels, it was perhaps not so hard to imagine that a malleable glass would be next. In this light, it is quite understandable to find a parable about glass upsetting the precious metals market.

We find yet another variation of the story in Richard Knolles' The General Historie of the Turkes (1621). In 1610, just as Neri was preparing to return to Florence, from Antwerp, we are told that "…among other rare presents sent to the king of Spain from the sophy of Persia there were six drinking glasses made of malleable glass so exquisitely tempered that they could not be broken." This version takes place at the same moment in history that Venetian style glassmaking skills were unleashed throughout Europe and just as new trade deals were being formed in the Far East. Glass was again rattling the balance of economic power.

In the 1697 translation of Neri by Blancourt, the story is embellished with a new twist, the rediscovery of malleable glass in France. In the reign of King Louis XIII (the son of Marie de' Medici), a beautiful glass figure was presented to the chief minister Cardinal Richelieu. In this version of the tale, the artisan was rewarded for his efforts with life imprisonment.

The story of flexible glass, in each case, emerges in a period of economic uncertainty caused by glass technology. In each case, the parable is redressed for the times, expressing new fears about economic stability. Tiberius' worry was the invention of glassblowing, for Philip III it was the emigration of Venetian glass masters and for Cardinal Richelieu it was the nascent industrial revolution knocking on his door. Often, these stories are cited as evidence of miraculous technical achievement. Perhaps they are better understood as signposts of social and economic developments in glassmaking.

Della Casa's Notebooks

Spine of volume 3 of Della Casa's notebooks,
Biblioteca Nationale Centrale Firenze.

Thousands of pages of notes relating to Antonio Neri's work in Florence were recorded by fellow alchemist Agnolo della Casa. A significant portion of this nineteen-volume transcript is devoted to Neri's work on transmutation and specifically on the fabled philosopher's stone. The trouble is that he wrote much of it in obscure language, which renders it among the most cryptic in the entire canon of alchemy. Other sections of Della Casa's notebooks contain copies of the works of various adepts including Geber, Ramon Llull and Arnold Villanova. Neri took a keen interest in all of them.

In 1597, Prince Don Antonio de' Medici occupied the dormant Casino di San Marco and made it his new home. His father, the former grand duke, built this combination palace and laboratory on the north side of the city to indulge his own fascination with natural secrets. Don Antonio began to assemble a team that included Neri and Della Casa. The three men were all about the same age, in their early twenties, ready to do great things; ready to reveal nature and change the world.

In their time, it was reasonable to think that one metal could be 'purified' into another and that a single medicine could cure all disease or counteract any poison. These notions had been around since ancient times. In this realm, a skeptical eye was an absolute necessity, but there was no specific evidence that disproved the old stories. Don Antonio reportedly spent a fortune collecting recipes and testing them; he and his men worked to separate the real from the bogus. Swindlers and con men were in plentiful supply; they hawked miracle cures in public squares throughout Europe. Without a firm grasp of the underlying chemistry, the task of understanding a particular compound or chemical reaction could be quite difficult. Even to experienced, careful researchers, there was no guarantee that conclusions were correct.

Don Antonio was convinced that the glassmaking priest had indeed discovered the secret of transmutation. He put Della Casa to work interviewing Neri's acquaintances to see what could be learned. An expert gold refiner, Guido Antonio Milani, reported to Della Casa that in July 1596, Neri had performed before his eyes a transmutation of base metal into "twenty-four carat" gold. He said he pressed the 20-year-old, who in reluctance, confided that he had learned the secret from a German, who performed the gold transmutation with a "tablet of medicine." The German told Neri the medicine was nothing but the simple quintessence of green vitriol and the method to produce it was described by Paracelsus.