GEM KNOWLEDGE · LABORATORY NOTES
Moonstone (Sri Lanka)
Moonstone beads from Sri Lanka, also known as Ceylon, tested to identify their feldspar composition.
Sample: 1534 (#5 moonstone). Report completed: November 1, 2025.
Finding: The beads are potassium feldspar, essentially orthoclase.
The optical detail
The report explains that orthoclase displaying adularescence is called moonstone. Thin exsolutions of another feldspar produce the optical effect; in these beads, the researcher describes a broader alignment of those exsolutions rather than the more random arrangement commonly seen.
Sri Lanka is the locality in our sourcing notes. “Ceylon Moonstone” and “Cat Eye Moonstone” are additional names used for this material. The report identifies orthoclase and describes its internal alignment; it does not provide a separate gemological grading of the cat-eye effect.
Also listed as: Ceylon Moonstone · Moonstone (Sri Lanka) · Cat Eye Moonstone.
View the original test results
Select a page to enlarge it.
These results are the property of Soul Body Gems, Alexander Falster, and the Maine Mineral & Gem Museum. Any mention requires full acknowledgment.
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 white hexagonal specimen 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 spectrum of spot 1 in Fig. 2. (potassium feldspar, orthoclase)
Read the report as text
Analytical Result Report Sample id: 1534 (#5 moonstone) Submitted by: Soul Body Gems Date completed: 11-1-2025 Operating conditions: An AMRAY 1830 SEM operated at 25 kV acceleration potential, 24 mm working distance, 0 degrees sample tilt, coated with 250 Å carbon, and also using the attached XRF unit operated at 30 kV. Fig. 1: Photograph of the specimen. Beads are about 7 mm in diameter. Fig.2: Backscattered electron image of an area of the white hexagonal specimen in Fig. 1. Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (potassium feldspar, orthoclase) Summary of findings: These are pretty stones (Fig. 1). The beads are potassium feldspar, essentially an orthoclase (Figs. 2 and 3). Orthoclase with the optical effect called ‘adularescence’ is referred to as ‘moonstone’. This optical effect is due to thin exsolution of a different feldspar, commonly it is more random whereas in these stones there is a broader alignment of these exsolutions. Date: 11-1-2025 Signature