Introduction

The purpose of this paper is to contribute to the study of the dress of the Virgen del Rosario through an integrated methodological approach that combines historical, artistic, and material analyses of gemstones used in the court fashion of Spanish women during the 16th and 17th centuries. To this end, a comparative study was conducted, combining the visual analysis of dresses and jewelry of queens and princesses depicted in contemporary paintings with the morphological and chemical examination of the metallic dress of the Virgen del Rosario from the same period. This approach allows a comprehensive understanding of fashion trends and jewelry production in the Spanish women’s court through both pictorial sources and preserved garments.

From the final years of the reign of Charles V until the late 17th century, thanks to the prestige of the Habsburgs, Spanish fashion prevailed throughout Europe, for both sexes, with the common characteristic of high, piped neck ornamentation and featuring ruffs1. Men dressed in black, because of the authority it confers on the wearer and because Spain had access to the best dye to obtain intense black (logwood) which was imported from America. Meanwhile, in women’s fashion, breasts were concealed with cardboard, planks and paper, with a reduced neckline. The use of a ruff, paired with cuffs, generated the impression of a complete shirt. Skirts were supported by farthingales, or petticoats with conical hoops, with a skirt or bodice and basquiña worn on the outside, making up a one- or two-piece dress, sewn at the waist. The result was a truncated conical figure with the main lines of the dress covered with brocade decoration, together forming a geometry of juxtaposed conical volumes. The colours were neutral and sober, such as black, grey, white and red. Very high cork platforms (chapines) decorated with leather or embossed metal were worn on the feet to increase height. Finally, large jewels were sewn onto dresses, alongside other decorations.

A closer examination reveals that gemstones commonly used in jewellery (earrings, necklaces, brooches, pins, crowns, etc.), were also employed to decorate textiles in combination with metallic threads, metal plates or sequins. A few rare artworks offer examples of ornamentation and fashion, as in the case of virgins with metallic dresses decorated with gemstones, such as the 17th century Virgen del Rosario dress held in the church of Santo Domingo in Granada, which is selected to evaluate as an example of women’s fashion in this period.

In the world of jewellery, Horcajo Palomero2 observes that the pieces reflected the historical era with a defined and international style, where the use of the noblest materials (gold and silver) were enriched by techniques as enamel, niello, etc., or gemstones such as diamond, ruby, emerald or pearls, among others, according to contemporary fashion. In addition to gemstones, natural or artificial glass or imitation stones were employed.

Additionally, Cellini describes that the use of doublets and triplets was common in 16th century3. Doublets consist of two stones, placed one on top of the other and joined at the centre or girdle. A cheap stone or glass is placed at the bottom, and the natural gemstone appears on top. As a result, this gemstone, though smaller in size, appears larger due to the addition of the lower piece. Triplets can be made with the same technique where a thin sheet of coloured enamel can be placed to enhance the stone’s colour. Some doublets and triplets were made of rock crystal or faceted stones, intended to imitate a diamond or other gemstones.

Furthermore, sewing jewellery onto dresses has its origins in 16th century, when these were placed on buttons and overlays on seams and openings, on the ends of ties or dotted throughout the garments. In accordance with sumptuary regulations4, jewellery had to be worn over clothing, with large pieces sewn on to support their weight. These jewels would then be swapped from one outfit to another, sewn and unstitched5, and served not only as ornamentation but also enrich and enhance the motifs of brocades and fabrics, frequently featuring inlays of diamonds, pearls and other gemstones.

In this context, the comparative approach was applied to the Virgin’s dress combined gemmological and chemical characterization of gemstones. This methodology made it possible to study which gemstones may have been incorporated into the dress during the 17th century and those likely added in other interventions, based on the evaluation of cut, colour symmetry and nature of stones. In this study, non-destructive and in situ analytical techniques played a fundamental role in the characterization of the gemstones, given that sampling or extraction was not possible, except for a few dropped gemstones. Numerous authors indicate that portable Raman spectroscopy proved to be especially useful for the identification of various gemstones and imitation glasses allowing for rapid and non-invasive compositional results4,5,6,7,8,9,10. The combination with other portable techniques became crucial to complement the analyses11,12. Several studies report that X-ray fluorescence (XRF) analysis provides valuable data on the chemical composition of both gemstones and imitation glasses, particularly regarding the presence of chromophore elements and the composition of the glassy matrix13,14,15. Additionally, other research demonstrates that Fourier transform infrared spectroscopy (FTIR) allowed for the confirmation of Raman and XRF results and contributed to identifying imitations16.

For the few detached gemstones, a more complete gemmological and chemical analysis can be carried out in a non-destructive way. Their main gemmological properties (such as refractive index, chemical composition, optical behaviour under polarized light, absorption spectra and inclusion features) can be analysed by scanning electron microscopy with energy-dispersive X-ray spectroscopy, refractometers, polarized and binocular microscope.

Methods

The methodology followed in this study is structured in three main steps. First, a comparative analysis was conducted between the dress of the Virgen del Rosario and the fashion of queens and princesses as depicted in 16th and 17th-century paintings. This was followed by a gemmological study, involving the inspection of the various gemstones present in the Virgin’s dress and their classification based on shape, cut, and colour. Finally, the study was complemented with the application of non-destructive analytical techniques to obtain additional information on the composition and characteristics of the gemstones.

Visual comparison of court portraits

A visual comparative analysis was carried out on the dresses represented in six paintings of queens and princesses from the court of Philip II of Spain, focusing on the depiction of fashion elements and the description of gemstones.

The court portraits analysed (Table 1) are housed in room 55 of the Prado National Museum (Madrid, Spain) and date to the same period as the clothing of the Virgen del Rosario. The Prado was chosen for its outstanding collection of full-length court portraits, which allowed in situ examination of garments and gemstones in detail. Access was granted through a special permit, enabling careful observation and photography under controlled conditions. These paintings represent the principal royal clothing typologies of the period, encompassing variations in colour, sleeve design, closures, and decorative elements. This selection facilitated a rigorous comparison of silhouette and clothing features between the Virgin’s attire and contemporary royal dress.

Table 1 Paintings of princesses and queens from the 16th century, Prado National Museum (Madrid, Spain) collection
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Gemmological study

The gemstones on the Virgin’s dress were characterised following gemmological and chemical techniques and compared with those described in the paintings. The gemmological study consists of the description of colour, cut and conservation state, as well as response to ultraviolet light.

There are 377 gemstones in the dress of the Virgen del Rosario. The smaller pieces are approximately 4 carats, while the larger are approximately 12 carats.

The dress of the Virgin is decorated with red, blue, yellow, green, violet, orange and colourless gemstones (Fig. 1). Red stones are the most common in the artwork (30%), mainly in the front of the skirt and on the left sleeve, while blue, green and yellow pieces are homogeneously distributed throughout the dress. Violet, orange and colourless pieces were largely found on the sleeves. The variability in gemstone colours and cuts generates asymmetry, in contrast to the systematically arranged gemstones on the dresses depicted in the studied paintings, suggesting different restorative interventions.

Fig. 1
Fig. 1
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Distribution of the gemstones in accordance with their group, colour and location of the Virgen del Rosario.

Most of the gemstones are step-cut or emerald-cut gemstones (≃80%/Group E). They present more or less elongated facets in the form of trapeziums, with edges parallel to the girdle (Fig. 2, square and rectangular emerald cuts). These commonly have three or four parallel facets and are mounted on the culet. Some present triangles or deformed pentagons in the apexes, rather than trapeziums. They feature an octagonal perimeter, while the relation between the axes permits their classification as square or rectangular. Emerald-cut gemstones usually have an intense blue, green, red or yellow colour. Green gemstones have two different hues, bluish green and bottle green, likely due to the thickness of the piece as the former have three trapezoidal facets, against the four facets of the darker ones. The state of conservation of these mountings is good. The shape of gemstones with emerald cut, as well as their good state of conservation, suggest that they could be replacements.

Fig. 2
Fig. 2
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Cuts observed in pavilion and crown on the Virgen del Rosario’s gemstones. © IAPH.

The second most abundant cut is the modified brilliant-cut (≃19%/Group B). These pieces have an octagonal perimeter with eight triangular or pentagonal facets and eight rhomboidal facets in their pavilion (Fig. 2, oval brilliant cut). Most of these gemstones colours are weathered, suggesting that they are composites; in other words, they are formed by two or three pieces (doublets or triplets) giving the appearance of just one17. Red and green gemstones show advanced alteration of the coloured glue that, in some cases, appears almost translucent due to the loss of the colour. These altered gemstones are commonly mounted in old-style mountings, frequently deformed, cracked and presenting material losses. Just one red gemstone with six rhombuses in its pavilion and pentagonal facets differs from the model, with a hexagonal perimeter like that of old brilliant cuts.

Less than 10% of the gemstones are mounted on their culet. These include step-cut pieces with rectangular (baguette), octagonal and square perimeters (carré) (Group C), and emerald cuts with square perimeters and one/two trapezoidal facets in their border (Fig. 2). These gemstones are red, yellow, orange, green, violet and colourless. Some of these pieces are altered with cracks.

Orange and reddish gemstones show modified dutch cuts (group F) in the front of the skirt and the right sleeve. This cut presents rhomboidal and pentagonal facets across the entire surface (Fig. 2).

In summary, the gemstones present a range of colours and asymmetry, where red is the most representative, and various cuts, which may relate to different chemical compositions and suggest different interventions in the dress. Because of that, the use of non-destructive techniques is a fundamental tool to assess the chemical composition of stones, providing additional information to determine whether the stones belong to the same or different periods, based on compositional variations or the presence of specific compounds linked to their historical development.

Non-destructive techniques

Chemical analysis of gemstones was carried out in a non-destructive manner by energy-dispersive X-ray fluorescence (EDXRF), Raman, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDS). In the present study, the analyses followed a specific workflow: first, portable techniques with qualitative measurements were applied in the following order: EDXRF, Raman, and FTIR; finally, SEM-EDS was carried out on dropped gemstones to obtain detailed morphological and semi-quantitative elemental data.

In-situ analysis was carried out using a handheld BRAVO Raman spectrometer (Bruker) in the automatic analytical mode with DuoLaserTM (two excitation lasers at 785 and 852 nm) which allows achieving a broad spectral range of 320–3000 cm−1 with a spectral resolution reported by the manufacturer of 10–12 cm−1. Spectra were acquired with acquisition times ranging from 3900 to 750 s and accumulations from 1 to 21. The spectrometer operates with SSETM (Sequentially Shifted Excitation), a patented fluorescence mitigation method (patent number US8570507B1) based on controlled temperature variations of the lasers over a small wavelength range. This approach enables fast and straightforward acquisition of Raman spectra with a corrected baseline based on fluorescence background subtraction18. All the measurements were processed using OPUS software. EDXRF spectroscopy was performed with a XRF Elio Bruker using a Rh X-ray tube, an accelerating voltage of 40 kV, a beam current of 20 mA and a measurement time of 90.0 s; data acquisition and analysis were conducted with Elio software. Additionally, a portable ATR-FTIR spectrometer (Agilent 4300 series) was employed to collect the spectra in the 650–4000 cm−1 spectral range with a resolution of 4–16 cm−1; the data were acquired using Agilent MicroLAB software and processed with Spectragryph software19.

Twelve dropped gemstones (Fig. 3) were studied with a SHIBUYA D-1 spectrometer, a ZEISS S21 binocular microscope and the MiSCope 2UV digital microscope equipped with visible, infrared and ultraviolet light and a JEOL 5600-LV scanning electron microscope. SEM-EDS microanalyses were performed using an Oxford Instruments Inca X-Sight with acceleration voltages of 15 kV and 100 s. To minimize sample alteration, analyses were carried out without metal coating under high vacuum conditions. This was achieved by optimizing measurement parameters (voltage and acquisition time), and by partially covering the gemstones with double-sided carbon tape, leaving the smallest possible exposed area to prevent surface charging.

Fig. 3
Fig. 3
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Gemstones detached from Virgen del Rosario (Granada). © IAPH.

Inclusions were observed using a Leica GZ6 binocular microscope with stereo zoom. The nature and optical behaviour of gemstones were studied with a KRÜSS refractometer to measures refractive indexes. A suspension of sulphur in methylene iodide was used to obtain good contact between the gemstones and the equipment. The dropped gemstones also were analysed with polarised light.

Results

The results are structured as follows: first, a comparative study of female fashion from the 16th and 17th centuries, based on selected paintings, applied to the dress of the Virgin of the Rosary. This is followed by a comparative analysis of the cut and colour of the gemstones represented in the paintings and those present in the Virgin sculpture and their location. Subsequently, the chemical and mineralogical characterization of the gemstones in the Virgin’s dress is presented. Finally, the last two sections address the study of the dropped gemstones through optical examination and SEM-EDS characterization.

Comparison study of clothing

The comparative study of the clothing of the Virgin and the paintings analysed shows that all the figures wear a wide skirt with a jubón (doublet) and a basquiña (overskirt), which appear as two cones facing each other (red line in Fig. 4), forming the truncated-cone shape.

Fig. 4: Comparative Analysis of the Virgin Sculpture and the Paintings.
Fig. 4: Comparative Analysis of the Virgin Sculpture and the Paintings.
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a Virgen del Rosario, Archconfraternity of the Holy Rosary of Granada, © IAPH; b Infanta Isabel Clara Eugenia and Magdalena Ruiz, oil on canvas 1585–1588 by Sánchez Coello; c Margaret of Austria, oil on canvas 1606 by Pantoja de la Cruz; d Elisabeth of Valois holding a portrait of Philip II, oil on canvas, 1561–1565 by Anguissola; e Infanta Catalina Micaela, oil on canvas, Ca. 1584 by Sánchez Coello; f Infanta Isabel Clara Eugenia, oil on canvas, 1577 by Sánchez Coello; g, h Infantas Isabel Clara Eugenia and Catalina Micaela, detail of oil on canvas, 1575 by Sánchez Coello. ©Archivo Fotográfico del Museo Nacional del Prado.

The Virgin (Fig. 4a) has a bodice fitted to the waist with a pointed bottom edge and a truncated cone edge. The sleeves are wide and fall to the ground, revealing the cuffs, which are also made of silver and are finished with natural fabric lace. The shoulder pad marks the junction between the torso and the arm. Gemstones border the front buttons of the bodice and skirt and the edges of the sleeves along with stones set symmetrically in stars and monograms representing the Virgin and Christ, imitating embroidery on fabrics.

This outfit aligns with the characteristics of the 16th–17th century women’s fashion observed in the court portraits, as they all (Fig. 4) feature marked profiles that accentuate verticality thanks to the decorative border on the front buttons of the skirt and bodice and on the edges of the sleeves (dark green line). The skirt or hem is fastened with cords or with stones and pearls (pink line in Fig. 4c–e). The basquiña shown in Fig. 4 (a, b, g, and h) features a fold in the skirt that can be loosened when sitting, ensuring the garment still covers the feet and shoes (yellow line). The wide, long sleeves (blue line) reveal the cuffs and vary in shape: pointed (Fig. 4a–d), round and wide (Fig. 4e), jacket-style or loose, sewn halfway up (“a la turca”), and decorated with almenas (crenellated flaps) and tejadillos (orange line). This style, common for children due to its comfort, appears in Fig. 4f–h. All depictions show cuffs embroidered with gold trim and collars with ruffles.

The truncated conical silhouette remains consistent, with jewels sewn onto the clothing emphasizing construction lines (dark green lines). Shoulder pads are marked by almenas and brahones (shoulder rolls), connecting cuffs to sleeves (light green and turquoise lines). Symmetrical embroidered motifs appear on the fabrics (light blue line), while on the Virgin, metal motifs with set stones imitate embroidery (Fig. 4a).

This 16-17th-century women’s fashion in the Spanish court is characterised by the decorum of the queens and princesses of the House of Austria as, through the refinement of their dresses, women represent the moderation of their manners and their religious customs—a new concept of femininity, which reflects the Christian ideology of the institution they represent20. As a result, the image of the queens and princesses acts as propaganda and a representation of the spirit at the court of Philip II. The farthingale, the cardboard chest, the chapines and the guardapiés erased the feminine forms and covered the whole body, as well as giving height and establishing a physical and symbolic distance from the rest of the court and the common people. This silhouette was magnified with the jewels that they wore sewn to their dresses, giving them a grand and solemn appearance.

This fashion was transmitted through the royal family’s practice of donating their own dresses to be used to clothe images of the Virgin. Notable examples include Elisabeth of Valois’s 1569 gift of a skirt embroidered with garnets, green stones, and enamelled gold buttons to the Monastery of San Clemente el Real in Toledo for an image of the Virgin with Child; Isabel Clara Eugenia’s 1598 donation of a skirt embroidered with gold, silver, and garnets; and queen Margaret of Austria’s gift of a skirt to the Virgen de la Caridad of Illescas21.

Cut and colour comparison

A total of 1634 gemstones were studied in the paintings (Table 2). Of these, 1592 were black, while 2.6% (42) were red. Black gemstones depicted in the paintings may represent diamonds. According to Arfe22, yellow and blue diamonds were considered less valuable than grey and transparent ones in the 17th century and, because of that, diamonds were dyed black on the reverse to achieve a steel-grey effect.

Table 2 Description of represented gemstones of paintings from the Old Royal Collection of the 16th–17th century, belonging to the collection of the Museo Nacional del Prado, Madrid
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Red is the most common gemstone colour in depictions of the Virgin sculpture (30%), while it is the second most represented colour in paintings (2.6%). The colour red has been related to royalty since the antiquity23.

More than 85% of the analysed gemstones of the Virgin are mounted on their table, with the pavilion exposed, contrary to the usual mounting observed in paintings representing jewellery in the 16th–17th centuries, where 87% of the gemstones were mounted on the crown. This mounting may have been selected due to the greater stability it offered the gemstone, placed on the largest facet, or the result of the lapidarist’s aesthetic criteria. All gemstones featured on the Virgin present a bezel setting, as with most of the gemstones observed in painting (42%).

Most of the gemstones featured on the Virgin are emerald cut (≃80%/Group E), while 78% presented a table cut in the painting, which may be associated with group C (<10%). Rose cuts are scarcely present in both cases.

The observed differences could point to the possibility of later modifications made to the gemstones incorporated in the dress.

Chemical and mineralogical characterisation of the virgin gemstones

The four groups of gemstones (B, C, E and F), classified according to their cut, present different compositions identified by XRF, Raman and FTIR that depend on cut and colour (Table 3).

Table 3 Main results of analysis conducted on the Virgen del Rosario using XRF, Raman and FTIR spectroscopy
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Group B

Red and green gemstones with modified brilliant cut are mostly quartzes. In contrast, the analysis of the blue stones was limited due to their placement on the garment, allowing only one to be examined, which was identified by Raman spectroscopy as a blue glass imitation (Fig. 5, Table 3). The Raman spectra for quartz gemstones (red and green colours) are consistent with those reported by several authors5,8,9,11,24. Some red and green coloured gemstones are quartz composites in which a paste has been used to give colour, which is commonly degraded, presenting a colourless quartz. Figure 6c shows the Raman spectrum of quartz detected in a green gemstone with an advanced state of alteration.

Fig. 5: Analyses performed on a blue glass with a modified brilliant cut.
Fig. 5: Analyses performed on a blue glass with a modified brilliant cut.
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A XRF spectrum showing the presence of copper as the main chromophore; B Raman spectrum displaying broad bands characteristic of glass nature.

Fig. 6: Raman spectra of several gemstones.
Fig. 6: Raman spectra of several gemstones.
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The Raman spectra of a ruby (red variety of corundum), b transparent beryl (goshenite) and c quartz.

XRF analyses indicate that the blue glasses contain copper as the main chromophore element, as shown in Fig. 5. These results are consistent with those reported by other authors for historical glasses, where copper has been identified as the only blue colouring agent in soda-lime and lead-rich glass pieces25, or in combination with cobalt to achieve different tonalities26. Additionally, iron was detected in one of the red coloured composite quartz stones, commonly associated as an impurity element in quartz27.

Group C

Colourless, red, violet, yellow and green gemstones with baguette, carré or octagonal emerald cut with the crown visible. In this group, quartz, coloured glass, beryl and corundum were found.

The transparent gemstones in group C are mostly rock crystal (colourless quartz), except for one identified as transparent beryl (goshenite) (Fig. 6). The red stones in this group include several quartz composites in which the colour is provided by a red coloured paste, some of which show signs of alteration. In addition, one red gemstone was identified as corundum with emerald cut in crown (ruby), according to Raman and FTIR spectroscopy (Table 3). The obtained Raman spectra align well with values reported in the literature8,11,16,24, confirming the presence of quartz, beryl, and corundum gemstones in this group.

The yellow stones are coloured glasses, according to the broad bands observed in their Raman spectra and further supported by FTIR analysis (Fig. 7, Table 3)10,16,28,29. The main chromophore contributing to the yellow colour is lead (Pb) while the presence of copper (Cu) may contribute to a more greenish hue.

Fig. 7: Analyses obtained on a yellow glass with an octagonal emerald cut.
Fig. 7: Analyses obtained on a yellow glass with an octagonal emerald cut.
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A XRF spectrum showing the presence of lead as the chromophore element; B FTIR spectrum display bands associated with the vitreous nature of the piece.

The violet glass imitations analysed in this group are characterised by the presence of iron (Fe), manganese (Mn) and copper (Cu) as chromophores. According to previous studies on historical glass30, Mn3+ is responsible for producing an intense violet colouration that can dominate over other chromophore contributions, such as iron and copper elements, which could introduce small variations in the hue. Raman spectra of these pieces show broad bands or low-intensity signals, with no clear evidence of crystalline phases, which is consistent with the hypothesis that these are coloured glass materials.

In addition, the presence of cobalt (Co) has also been found in the blue stone and copper (Cu) in the green stone.

Group E

Red, blue, yellow and green stones with modified emerald cut show broad Raman bands which may be indicative of an amorphous structure28,31. These Raman spectra do not exhibit the sharp features typical of crystalline phases and are therefore consistent with glasses, as shown in Table 310,28,29,32.

Yellow glass imitations studied by XRF show two types of chromophores: (1) lead (Pb), used since ancient times, where glass have small aggregations of lead oxide33; and (2) arsenic (As), where an arsenic sulphide compound may be responsible for the colour13,34.

The blue glass imitations present two types of chromophores: (1) copper (Cu) associated to Cu2+ as the main chromophore element25; and (2) iron (Fe), associated to Fe2+ 30.

All the red glass imitations are associated to CdS+CdSe (cadmium red) as chromophores. Although cadmium-based compounds began to be commercialised after 1840, their widespread use as colouring agents in glass became common by the 1920s35. Later, in 1977, Wagner patented an industrial process for producing firing-stable yellow to red glaze mixtures based on cadmium pigments36. This evidence suggests that all these stones were replaced from the beginning of the 20th century onwards.

Finally, all the green glass imitations contain copper and iron as chromophore, probably added to the base glass to obtain the green colour14.

While most of the pieces studied in this cut group have a glass nature, there is a violet gemstone identified as amethyst (quartz, violet variety), according to the Raman spectrum (Table 3). This feature may suggest a replacement that occurred after the artwork’s creation but non-contemporary with the employment of glasses.

Group F

Red and orange gemstones with modified dutch cut. Two orange gemstones have been identified as citrine (a variety of quartz). Meanwhile, the red modified Dutch gemstone has been identified as ruby (red corundum).

The Raman spectrum of ruby (red corundum) is shown in Fig. 6a, while the characteristic bands obtained in the Raman analysis are listed in Table 3 in agreement with reference values24,37,38.

Optical study

Optical study was carried out on dropped gemstones. Violet and colourless gemstones were anisotropic, uniaxial and with refraction indexes similar to amethysts and smoky quartzes, according to the results obtained by Raman and FTIR spectroscopy. These gemstones also showed small bubbles and solid inclusions. The yellowish piece was identified as citrine quartz, while a red gemstone with emerald cut showed anisotropic behaviour with polarised light and refraction indexes like corundom. This latter gemstone also presented light fluorescence with ultraviolet light. The colour of this ruby is due to chrome (Cr), according to the doublet observed in the absorbance spectra, though this was not detected by XRF.

Green and blue pieces with emerald cuts mounted on their table were isotropic with a refraction index ≃1.500, whereas the other red piece presented a refraction index of 1.788, due to a different chemical composition. In both cases, these values are consistent with glasses and vary according to their composition.

SEM-EDS analyses

The SEM-EDS analyses were carried out on dropped gemstones with a suitable size and geometry to avoid dispersion of the electron beam (Table 4).

Table 4 Chemical composition in the gemstones analysed by SEM-EDS (wt%)
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Amethysts (quartz) presented high silica content (G2, G4 & G7), while the three step-cut gemstones showed a chemical composition similar to glass (Table 4). The green and violet gemstones were soda-lime silicate glasses with a high content of SiO2 (A1 and G1); while the red gemstone was a lead silicate glass (G9). The high content of lead in this latter gemstone induced a higher refraction index. The addition of lead to glass makes it easier to carve and increases its shine, improving the quality of the synthetic gemstone. While glasses from the ancient (Mesopotamian, Egyptian or Roman) period are usually soda-lime silicate glasses with a high content of impurities due to the low purification of raw materials39,40, with the development of better melting furnaces, higher temperatures could be reached for long periods of time, facilitating the melting of glasses with higher silica content41. Glasses with a high content of lead have been found in Spain since Roman times42,43. These glasses were brighter, easier to cut and engrave, and presented lower melting temperatures than the soda-lime silicate glass, though they were also more fragile and heavier44.

Discussion

The combined study of the paintings and gemmological characterisation of gemstones establishes that the dress of the Virgen del Rosario followed the fashion of 16th and 17th-century queens and infants, though the gemstones themselves correspond to different periods.

The portraits of queens and princesses from the 16th and 17th centuries, compared with the silver dress worn by the Virgen del Rosario of 1628, show that the Image’s costume follows feminine fashion in Spain—characterised by the use of breast cardboard, the farthingale and chapines, undergarments that form a rigid, truncated-conical silhouette on the outside.

The portraits studied, as well as the Virgin image, projected the position of the women of the elite, reflecting the aesthetic and moral values adopted in Spain with the Counter-Reformation. The typology of the clothing complies with the provisions of the sumptuary laws, such as the modest clothing that completely covered the body, hiding their forms, and the use of sober colours—although the richness of the fabrics and the profusion of jewellery does not align with that dictated by pragmatics and is opulent in both portrait and statue.

Jewellery became an important part of clothing, as dresses were composed and closed with pieces of jewellery sewn into the seams and openings. In the jewellery of the studied paintings, large gemstones with simple cuts (table and cabochon) stand out, taking advantage of the size of the stone. The gemstones were set in a box, in the direction of the crown.

The costumes of the queens and princesses featured stones represented in black—possibly diamonds tinted on the reverse—and red stones, which could be rubies, spinels, tourmalines, garnets or glasses. These are arranged on necklaces, belts and buttons in the paintings, arranged symmetrically on clothing, marking the lines and accentuating the verticality of the image represented.

The gemstones on the Virgin’s dress are of different colours, among which red predominates, differing from the paintings studied, in which this colour is the second most frequent. The carvings are mostly more faceted and complex, with the majority mounted in a reverse direction. In fact, the great variety of colours and cuts in the dress makes it difficult to find symmetries therein, in comparison with the symmetry observed in the dresses of the paintings studied, suggesting different restorations.

In the Virgin, glasses and composites predominate over natural gemstones (quartz (amethyst and citrine), corundum (ruby) and beryl (goshenite). The glass imitations are the most common in the dress of the Virgin (group E). Because of that, for all colours, the proportion of glasses is higher than natural gemstones, except in the case of violet, where quartz amethysts are more abundant. While the identification of quartz, corundum, and beryl yielded high-quality Raman spectra, the analysis of glasses is inherently more challenging due to the combination of fluorescence and broad bands from the glass itself which might produce band-like artifacts in the spectra, a limitation of the background subtraction performed by the instrument45.

The glasses with emerald cut (group E) may be recent interventions of the 20th century, as the chromophore found for red stones was widespread as colouring agents in glass by the 1920s. Moreover, the glasses present two different compositions according to SEM-EDS results: soda-lime silicate and lead silicate glasses, which may derive from two different chronologies or two different workshops.

Around 20% of the gemstones are composites with brilliant-cut (group B) of colourless quartz with alterations in their coloured paste, mainly in red and green pieces. Other composites have been found on red stones in group C, also based on quartz and a red paste as chromophore.

Composite gemstones (doublets and triplets) were used in the 16th century, as well as glass imitations enhanced with treatments3, these handmade pieces make them appear larger with high quality and intensive colour. As such, the glass or composite gemstones on the Virgin’s dress may derive from its original period. Nevertheless, the brilliant-cut (group B) suggests a later intervention while the red composite of group C could belong to the original period, as their cut is set on crown like those found in the paintings.

The Raman, FTIR and XRF spectra, refraction index and their optic behaviour permitted the identification of amethysts, citrine and smoky quartzes, as well corundum (ruby) and beryl (goshenite) (group C and F). These simplest cuts mounted on the crown may correspond to the period of the metallic dress’s production, given the comparison with those cuts found in the paintings and their natural origin.

Red and orange gemstones with modified dutch cut (group F) have been identified by Raman as two citrine quartzes and one ruby, and also could be from the original period, as dutch cut was employed since 16th century and could be found in pictures as Venus embraced by Cupid (Bronzino, circa 1546, Nacional Gallery, London) and rosa cut is also employed in the picture of Elisabeth of Valois holding a portrait of Philip II.

In summary, the integration of historical-artistic analysis, the typology and chronology of gem cuts, and the compositional analysis allow to ensure that the dress of the Virgen del Rosario follow the fashion of the queens and princesses of the 16th–17th century while suggests the existence of at least three historical phases of jewellery interventions on the dress. The natural gemstones with modified dutch cut (group F) and mounted on their crown (group C), appear to be oldest and may be contemporary with the dress and the pictures studied. Group B, mostly composed of composite gemstones based on quartzes with brilliant cuts, may correspond to a second intervention phase. Although composites are contemporary to the dress and this cut spans from the 17th to the 20th centuries, the brilliant cut may suggest a more recent origin than those in groups C and F due to the comparison with portraits. Finally, the red, yellow, green and blue glasses of group E appear to be the most modern, as the presence of cadmium red was not used until the 20th century.

This information can be of great interest for future interventions or for studies of similar artworks. The combination of historical-artistic study with non-destructive analyses is highly valuable for understanding the evolution of an artwork. Identifying previous gemstone replacements, the materials used, and the type of cutting provides important insight into the historical period of their placement and the resources available. Furthermore, this information may guide more respectful interventions, prevent historical inaccuracies, and help assess the current state of conservation of these materials, thereby supporting preventive conservation and the long-term preservation of the artwork.

In conclusion, the comparison of clothing allowed an identification of the Virgin’s dress as aligned with women’s dress in the 16th and 17th centuries, while the gemmological study clarified aspects related to the different interventions detected in the Virgen del Rosario. The sculpture of the Virgen del Rosario (Granada) presents a great variety of gemstones and glass imitations with different colours and cuts, wherein the gemmological and chemical characteristics may suggest at least three different interventions. These findings highlight the importance of an interdisciplinary approach to study the history of the artwork, where iconographic study, gem-cut typology and non-invasive chemical analyses converge.

The use of non-destructive techniques combined with gemmological description employed in this study has allowed the characterisation of gemstones and its comparison with portraits. This methodology, combining historical analysis of portrait and gemmological and non-invasive characterisation is very useful to analyse gemstones, composites and glass imitations, allowing a first approach to evaluate the historical context and sequence of their placement or replacement. Anymore, further studies based on quantification of chemical composition and the use of complementary techniques may allow to gain in-depth knowledge about the gemstones.