GEMMOLOGICAL AND SPECTROSCOPIC STUDY WITH MOBILE INSTRUMENTS OF THE “EMERALDS” FROM THE FRENCH CROWN JEWELS

International audienceRare are the scientific studies on gemstones from the French Crown Jewels, for the good reason that most of them were sold away by the French Third Republic in 1887, to get rid of this symbol of Royalty and Empire. Some unset stones were however put aside from the big sell, and given to some French museums, including the French Natural History Museum, the Louvre, and the Paris School of Mines. Some jewels have been bought back since the late 20 th by the Louvre, but mostly, the Crown Jewels are still spread out around the world. This paper is part of an ongoing project on the study of the French Crown Jewels owned the Paris School of Mines since 1887, in collaboration with the French Gemmological Laboratory (LFG). As this National Treasure is security sensitive, the project had to be conducted on site at the MINES Paristech Mineralogy Museum, using portable analytical instruments. In this first study, we are presenting the results acquired on some green coloured gems that used to be part of the coronation Crown of Napoleon III

Gemological study of emeralds from the Crown of Napoleon III at Paris School of Mines

International audienceAs most of the French Crown Jewels, the Coronation Crown of Napoleon III was dismantled in 1887 prior to the large auction intended to get rid of the foremost symbol of Royalty and Empire. The crown was created by the Emperor's jeweler, Alexandre Gabriel Lemonnier in 1855, depicting 8 golden eagles and palm leafs, adorned with diamonds and emeralds. The large 8 emeralds were given back to the Empress Eugenie, while the large 8 diamonds and other smaller diamonds were sold in 1887. The smaller 50 emeralds were put aside and donated to the Ecole Nationale Supérieure des Mines de Paris-Paris School of Minesbefore the auction (Morel, 1988). Lemonnier also created a similar but smaller crown for Empress Eugenie, which was kept in her family and eventually donated to the Louvre museum in 1988. In this study, we are reporting for the first time a gemological study of the remaining 45 emeralds in the collection of Paris School of Mines (Figure 1: 8 main emeralds, ENSMP69866). Our examination revealed that 41 out of 45 gems were indeed natural emeralds, presenting no evidence of clarity enhancement. Because of their gemological characteristics, we could established their provenance to most likely be Colombia, especially that they were mounted in 1855. Four samples however found to be artificial glass, possibly set on the crown since the beginning. This study is part of a worldwide intention of studying gemstones of historical meaning and significance

Gemological study of an emerald reportedly from Egypt in Paris School of Mines museum

International audienceParis School of Mines Mineralogy Museum holds a collection of about 2,000 gemstones on top of its extensive collection of minerals of almost 100,000 specimens, built over the last 230 years. Some gems have historical values, such as an emerald reportedly from Egypt (Figure 1, ENSMP 69845). The exact acquisition date of this gem is unknown, but regarding its label and catalog number, it is estimated at the mid- to late 19th century (Gaillou et al., 2022). At the same time, rough emeralds from Egypt arrive in the collection, coming from the great expeditions of French explorer Frédéric Cailliaud (1787 – 1869; Cailliaud, 1821, Mainterot, 2012). Four other rough Egyptian emeralds are bequested to the museum in 1910 by Emile Bertrand, reportedly collected from “the ruins of Alexandria”, which would represent the historic deposits mined until the fall of pharaoh Ptolemy IV in 145, and not the rediscovery of Cailliaud in the early 18th century. These different sets of rough material would therefore be reference samples for gemological research.The purpose of this study is to compare the gem emerald with other samples in the collection, confirm or rebut its origin, characterizing at the same time all the samples from this historic and emblematic deposit. First, we investigated the gem, and we are now conducting analyzes on the rough samples. The gem emerald is a faceted deep green, highly included gem, weighing 3.19 ct. Under the microscope, the examination revealed indeed numerous inclusions, some of them multiphased with jagged outlines as well as gota de aceite patterns. Ultraviolet – visible spectroscopy revealed absorptions due to chromium and vanadium, without absorption bands related to iron. Fourier Transformed Infrared spectra present bands linked with low alkali content. Chemical analyses further confirmed the above observations. These data are similar to emeralds from Colombia and not to what is known about Egyptian emeralds (Saeseaw et al., 2014; Karampelas et al., 2019). We are currently studying the other rough Egyptian emeralds in the collection in order to compare them with this sample, especially the ones from the Cailliaud expeditions, which have not been studied until now

A Gemological and Spectroscopic Study with Mobile Instruments of “Emeralds” from the Coronation Crown of Napoleon III

International audienceForty-five “emeralds,” formerly set in the coronation crown of Napoleon III, were studied using nondestructive mobile spectroscopic and gemological means. Adorned with emeralds, diamonds, and gold, the crown was created in 1855 by royal jeweler Alexandre Gabriel Lemonnier but dismantled in 1887 for the auctioning of the French crown jewels. Some of the emeralds were donated to the École des Mines (Paris School of Mines, now known as Mines Paris - PSL) in 1887, prior to the auction. Our examination revealed that 41 out of 45 gems were indeed natural emeralds, presenting no evidence of clarity enhancement. Their gemological characteristics and age suggest a Colombian provenance. The other four samples were determined to be artificial glass containing iron and/or copper and possibly other chromophores. These glass imitations could have been set when the crown was created or shortly thereafter. This study is part of an effort to examine gemstones of historical meaning and significance worldwide