gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology

Jade, the most valued of all Maya products, is very scarce or does not occur in the Yucatán Peninsula. Foshag (1955, p. 11), in listing seven varieties of jade found in archaeological collections from Middle America, notes the intimate association of jade in situ with serpentine deposits and points out that they normally have an enveloping skin of albite in the process of conversion into jade. He observes that where there are deposits of serpentine there is a good possibility of finding jade, and lists the following known deposits: the Sierra de las Minas north of the middle Motagua, with an outlying spur south of San Agustín Acasaguastlán; the Sierra de Santa Cruz northwest of Lake Izabal; the Sierra de Chuacús in northern El Quiché north of the Río Negro and extending into adjacent Baja Verapaz; and a small area north of Huehuetenango. More recently, jade was actually found in situ near Manzanal in the Sierra de las Minas (Foshag and Leslie, 1955). Small deposits of serpentine are situated, according to Sapper, near Chimalapa in southern Chiapas, close to the Guatemala border. Of these areas—and it must be remembered that, except for Manzanal, jade had not been found anywhere; the rest were only potential sources—only the Sierra de Santa Cruz and perhaps the northeastern end of the Sierra de las Minas are in lowland territory. Whether there is jade in these two areas, and whether the Manche Chol who inhabited the region (they were called Toqueguas there but were of Chol speech) worked it if it existed there, are uncertainties. Pusilhá and Lubaantun, which were in Chol territory at the time of the Spanish conquest, have not shown much evidence of jade wealth, and the same is true of Quiriguá, which lies in territory probably occupied by the Chol in the sixteenth century. On the other hand, the relatively insignificant sites of Pomoná, Kendall, Camp 6, and the not very important Mountain Cow, to the east and west of the Maya Mountains in British Honduras, have yielded some very fine worked jades in the course of quite minor excavations. One is led to speculate whether there could be jade in that range.

gems, jade, pyroxene jade, fei cui, jadeite, dyed jade, treated jade, composite jade, plastic-coated jade

We have commented on the variable fastness of the colors used in dyeing jadeite. We recently tested some dyed stones of excellent color. The owner stated that he had purchased them in 1955—a full year before we first encountered the stones in the course of our testing work. He further stated that to his recollection they had not faded. In another note, a necklace of round jade beads showed the treated spectrum and the normal jadeite absorption line at approximately 4370 Å, but the refractive index was approximately 1.55 by the spot method. Magnification revealed that the stones were plastic coated, in addition to being dyed; hence, the “wrong” refractive index for jadeite. And another note: Figure 3 illustrates a small, flat, oval cabochon of jadeite, one of a group that a manufacturer stated had altered radically in appearance following normal steam cleaning of finished jewelry. What had originally been evenly colored medium-green stones became mottled with numerous white, intersecting cracks. The only suggestion we could offer was that perhaps the stones had been oiled to camouflage the cracks before they reached the manufacturer.

gems, synthetic beryl, synthetic beryl, emerald, Gilson

Description of Gilson synthetic emeralds.

sugar-treated opal, treatments, gems

corundum, sapphire, Brazil.12, geology.11, gems

About four years ago, Professor J. E. de Souza Campos of the University of São Paulo, Brazil, reported on a new sapphire from Brazil. He mentioned strange inclusions, unknown until now in sapphire and resembling rounded gas bubbles so typical of synthetic corundum. At the author’s request, Professor de Souza Campos very kindly made available two cut stones of this sapphire and later some raw material, which could be tested more easily. The locality of these sapphires is quoted by de Souza Campos as Jauré and Quilombo, Rio Coxim, Mato Grosso. He found the refraction for sodium light to be nₒ = 1.770, nₑ = 1.762, and the birefringence 0.008. The dichroism for blue-coloured stones is o = blue to violet blue, e = green; for greenish-coloured stones o = green, e = yellow-green. With the hydrostatic balance he determined the specific gravity at 3.952 to 4.052. The stones exhibit a dark blue colour but, regrettably, the transparency is considerably reduced by many inclusions. At a first sight through the microscope, many of them indeed resembled rounded gas bubbles. But when using a higher magnification, it is seen that two kinds of inclusions are present: liquid and gas-filled discs, and negative crystals, many of them exhibiting rounded forms.

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology, Pre-Columbian jade; Costa Rica; Maya; exchange; iconography, lapidary, fashioning

To their great amazement, the Spanish conquerors found that in Mexican eyes the most precious objects were not of gold, but rather were fashioned from various green stones which eventually came to be known as “jade.” As the author shows in her very useful summary of ethnohistoric sources on Aztec lapidary techniques, the workers in fine stones were organized into a guild, supposedly originating in Xochimilco. But Aztec lapidarians had in back of them no fewer than 25 centuries of experimentation, most of it carried out without the benefit of metal tools. Part II presents a brief summary of techniques; these were largely restricted to percussion, drilling with tubular and solid instruments, string abrasion, polishing, and burnishing. The advent of tubular copper drills, after A.D. 900, must have opened up all sorts of possibilities for stone cutting, to which the fine onyx bowls of Post-Classic Mexico testify. The most important section of the monograph is Part III, in which the author analyzes, by means of the binocular microscope, a variety of stone objects to discover their means of manufacture. For each artifact class (beads, ear spools, plaques, etc.) there are established discrete technical modes, which are presented for each site in tabular and graph form. Unfortunately, some of the graphs and tables have misprints, so that their usefulness is diminished. I suspect that the last word has not been said on the full range of lapidary techniques employed in ancient Mesoamerica. For instance, in spite of what the author says about the concave, hematite mirrors of the Olmec or the paper-thin obsidian earspool of Post-Classic Mexico, the ways that they were produced still remain a mystery. Perhaps it is not so much laboratory analysis, but actual experimentation in reproducing these marvelous objects that will throw light on some of these problems.

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology

Robert Woods Bliss’s Collection of Pre-Columbian Art was formed by the strong personal interest of a man deeply engaged in his subject. The Collection is most unusual in that its objects are not merely of archaeological interest but were chosen by Mr. Bliss for the intrinsic beauty of their craftsmanship and materials. Mr. Bliss’s first purchase was an Olmec sculpture in Paris in 1912 (Handbook no. 25). During the succeeding years, while he and Mrs. Bliss were forming their Byzantine Collection and establishing Dumbarton Oaks, Mr. Bliss also acquired pre-Columbian objects. He collected more intensively in the 1940s and 1950s, after Dumbarton Oaks had been conveyed to Harvard University, and continued to do so avidly until the time of his death in 1962. Mrs. Bliss always shared his interest in the Collection, and has recently added to it several objects which he no doubt would have selected himself. By the mid-forties, the Collection had assumed such importance as to be of public interest, and, in April 1947, it was placed on exhibition at the National Gallery of Art. There it remained, its size and area of installation expanding, until July 1962. Thus, during these sixteen years, many people were given the privilege of studying and enjoying the Collection. Mr. Bliss was eager to have the indigenous arts of the Americas represented permanently in the capital of this country. He made the happy decision to give his Collection to Dumbarton Oaks, and Philip Johnson was chosen to design a building for it. Mr. Johnson has created an original and beautiful setting where the objects are seen as works of art, arranged according to cultures. Except for the more recent accessions, largely generous gifts whose sources are noted in this handbook, the entire Collection was acquired by Mr. Bliss himself.

gems, early lapidaries, early gemology, early mineralogy, herbals, gems and healing, medicinal gems

Of the spurious work of Galen on forty-six plants and occult medicines there appear to be two different Latin translations from the Arabic, yet both executed at Marseilles, both from the earlier rendering from the Greek into Arabic which Ḥunayn ibn Isḥāq (Johannitius) had made in the second half of the ninth century, adding a commentary of his own, and both with the help of a Jew from Tortosa named Abraham. Of the Latin translation by Grumerus, a judge of Piacenza, which was discussed in my History of Magic and Experimental Science, II, 763–64, after the printed edition of Venice, 1609, there are also at least two manuscripts, both of the fifteenth century. At the Vatican, Palatine 1100, fols. 1–3v, is a parchment codex, but the first leaf is worm-eaten and in a bad state of preservation. In the Laurentian Library at Florence, Ashburnham 1448 (1371) is a paper quarto, with the date Feb. 3, 1434, at fol. 155v. Our treatise begins at fol. 109v, but breaks off at fol. 114v, in the midst of the account of the forty-second plant. Fols. 115 and 116 are now missing from the manuscript.

corundum, Australia.12, inclusions.5, gems

Examination of a parcel of approximately thirty blue Australian sapphires reveals exceptionally closely spaced growth zoning that can resemble the fine striations associated with synthetic corundum. The stones, submitted by John Fleming of New Zealand, attracted attention because their growth bands were of a similar order of size to those seen in synthetic material. Although the observed striations showed no curvature, this distinction alone was insufficient to resolve their origin immediately: in small stones fashioned from a large synthetic boule, curvature may be inconspicuous, particularly under strong magnification. The report therefore identifies a potential difficulty in interpreting fine zoning when only a limited portion of a growth structure is visible within a faceted stone. Further microscopic examination disclosed convincingly hexagonal zoning in some specimens, together with healed fractures, providing additional evidence for their identification as natural sapphires. Photomicrographs illustrate both the closely spaced straight bands that initially prompted concern and the more diagnostic hexagonal pattern found during the subsequent investigation. Other observations document the physical and optical characteristics of the parcel. Testing in Clerici solution showed the stones to have densities slightly greater than that of a reference sapphire with a density of 3.995, although individual numerical determinations were not reported. Refractive indices measured with a Rayner refractometer in sodium light ranged from 1.765 to 1.780. Dichroism was pronounced, producing green and purple shades of the blue body colour. Examination between crossed nicols revealed neither strain nor twinning, and no further features of particular interest were recorded. The stones were described as richly blue but somewhat dark. The principal contribution is the documentation of unusually fine natural growth zoning whose scale and appearance approach those of synthetic corundum. Its diagnostic implication is that closely spaced striations should be assessed through their geometry and associated internal features, with particular attention to the possibility that a small field of observation can conceal curvature. The note offers an observational account of this identification problem rather than an explanation of the geological conditions responsible for the exceptionally narrow zones.

corundum, gems

Farn outlines a systematic approach to ruby identification, emphasizing the distinction between establishing a stone as corundum and determining whether it is natural or synthetic. Although experienced observers may recognize characteristic appearances and inclusions immediately, he argues that laboratory conclusions require corroborating tests rather than intuition or commercial reputation. Refractive-index measurements and the characteristic chromium spectrum establish ruby but do not distinguish natural from synthetic material. The spectrum is described through its red doublet, broad absorption across the yellow-green region, and fine absorption lines in the blue; Farn favours spectroscopy for small or worn stones because it avoids contact with the comparatively soft refractometer prism. Microscopic examination provides the principal evidence of origin. Features discussed include rutile silk, mineral crystals, twin planes, feathers, and the uneven colour distribution termed “treacle,” which Farn associates particularly with Burmese rubies. He contrasts these with features observed in Siamese material, including distinctive halo-like feathers surrounding opaque inclusions, while acknowledging that commercial geographical labels may follow colour and appearance rather than actual provenance. Particular attention is given to misleading similarities: natural crystals may resemble gas bubbles, synthetic bubble groups may suggest natural feathers, and internal colour effects may resemble striae in glass. Comparison specimens and repeated observation are therefore recommended. For apparently inclusion-free stones, immersion in a liquid approaching ruby’s refractive index reduces surface interference and assists the search for bubbles or curved growth structure. Farn describes rotating the specimen while adjusting focus, condenser height, diaphragm aperture, and illumination angle to reveal faint internal features. Excessive magnification may obscure slight curvature by restricting the visible length of a growth line, while focusing beneath the specimen can mistakenly bring bubbles or striae in the glass immersion cell into view. When microscopy remains inconclusive, he discusses X-ray transparency, X-ray-excited fluorescence and phosphorescence, and immersion contact photography. He regards phosphorescence following X-ray excitation as strong evidence of synthetic origin, illustrating the need for continued observation with a specimen whose afterglow appeared only after a delay. Short-wave ultraviolet fluorescence is treated more cautiously: differences in brightness may assist comparison within a parcel, but variation among natural rubies prevents its use as an independent diagnostic test. Immersion contact photography can disclose curved structure that escapes direct microscopic observation, and simple low-power examination against a diffusely illuminated white background may also prove effective. Throughout, Farn stresses the difficulty created by the closely similar optical and chemical properties of natural and synthetic ruby. His central conclusion is that careful interpretation of internal structure and inclusions, supported by complementary tests where necessary, provides the strongest basis for identification.