GEM KNOWLEDGE · LABORATORY NOTES
Turquoise (constituted)
This vivid, uniform turquoise bead strand raised a question about its manufacture. The title records a suspected process, not a proven determination for every bead.
Finding and uncertainty: Sample 92958 contained mainly aluminum and phosphorus with copper in the turquoise range. The beads were strikingly homogeneous. The researcher was skeptical that their present form was wholly natural and proposed two possibilities: constituted material made from ground turquoise, or synthesis from appropriate starting materials. Possible carbon could point to epoxy. The report does not conclusively distinguish those possibilities.
Tested specimen: Bead strand, beads about 2.5–3 mm across, report completed April 3, 2023. This is an example of why appearance and color alone cannot establish treatment or manufacturing history. It does not show that high-grade turquoise in general is constituted.
View the original report
Select a page to enlarge it. Three pages; findings are summarized in accessible text above.
Understanding the report figures
Use this guide alongside the written findings and the original report transcript. It explains the purpose of each analytical figure and preserves the laboratory’s own figure labels. The interpretations apply to the tested specimen; signals alone do not establish the identity of every similar-looking stone.
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Electron microscope image: This view shows small-scale regions selected for analysis. Its brightness contrast helps distinguish regions with different compositions; it is not a photograph of their natural colors. Numbered spots connect this view to the analyses listed in the report.
Laboratory figure caption: Fig. 2 Backscattered electron image of an area of the specimen shown in Fig.1.
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Elemental spectrum: The peaks record characteristic X-ray signals from elements in the analyzed spot or area. This is an analysis of that location, not automatically of the entire specimen. Any mineral identification or uncertainty named in the laboratory caption is retained below.
Laboratory figure caption: Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2 (aluminum phosphate with minor copper, looks like turquoise).
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Element map: This map shows where the named elements occur within the analyzed area. Its colors represent the laboratory’s selected element channels, rather than the specimen’s visible colors. The caption below preserves any color key or distribution noted by the laboratory.
Laboratory figure caption: Fig. 4: X-ray map of aluminum (red) and iron (green). Note very uniform distribution of the elements.
Read the original laboratory report as text
The following text and tables are transcribed from the original laboratory document. Figure captions identify the report images; the laboratory interpretations and limitations are preserved.
Laboratory report 1
Analytical Result Report
Sample id: 92958 (turquoise bead strand)
Submitted by: K. Bitner
Date submitted: March 23, 2023.
Date completed: April 3, 2023.
Operating conditions: An AMRAY 1830 SEM operated at 25 kV acceleration potential, 26 mm working distance, 15 degrees sample tilt, coated with 250 Å carbon. Using the X-ray fluorescence attachment with 35 kV potential in conjunction with the EDS system.
A Bruker Titan X-ray fluorescence spectrometer was also used and operated with 50, 25 and 10 kV.
Fig. 1: Photograph of the specimen. Approximately 00.25-0.30 cm diameter of the beads.
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Fig. 2 Backscattered electron image of an area of the specimen shown in Fig.1.
Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2 (aluminum phosphate with minor copper, looks like turquoise).
Fig. 4: X-ray map of aluminum (red) and iron (green). Note very uniform distribution of the elements.
Table 1: Minor and trace element composition of the dark blue area of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Aluminum | 19.3 |
| Calcium | 0.05 |
| Copper | 2.0 |
| Iron | 0.4 |
| Manganese | 0.01 |
| Phosphorus | 13.2 |
| Titanium | 0.06 |
Summary of findings: This specimen is very interesting (Fig. 1). Compositionally, the beads consist of dominantly aluminum and phosphorus (Figs. 2 and 3, Table 1). The beads are very homogenous (Figs. 1 and 4). No irregularities or streaks of manganese or iron oxides are noted. Chemically, it has the correct elements, a little low on the copper than most turquoise but still in the range so it is chemically the correct material. As to naturally occurring as we see the beads now, I am skeptical. I think they have either been constituted from ground up turquoise, if not completely synthesized from the proper oxide. A little iron titanium etc. may suggest that natural turquoise was used. Another point is the presence of some carbon (Fig. 3) which could indicate presence of some epoxy to solidify the material.
Date: April 3, 2023 Signature