GEM KNOWLEDGE · LABORATORY NOTES
Malagasy Moonstone
Sold as Malagasy Moonstone or Rainbow Moonstone, this Madagascar gemstone tested as labradorite. Malagasy Rainbow Labradorite is the corrected name used here.
Sample: 10622 (number 1). Completed: August 8, 2024.
Finding: Intermediate plagioclase in the labradorite compositional range.
Labradorite behind the market name
The report identifies the faceted stone as labradorite. Its measured density of 2.71 g/cm³ and refractive index of approximately 1.57 agree with that identification. The trade-name moonstone entries lead to the same results so visitors can find the distinction.
Locality: Madagascar, according to Soul Body Gems sourcing notes. The tested gemstone weighs 0.94 carats.
Also listed as: Malagasy Moonstone · Rainbow Moonstone (Madagascar) · Malagasy Rainbow Labradorite.
More from our August 2025 collection
The laboratory findings below identify only the individual submitted specimens, not every photographed necklace or bracelet.
View the original test results
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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 specimen.
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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. (plagioclase, labradorite compositional range)
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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.
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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. (plagioclase)
Read the report as text
Analytical Result Report Sample id: 10622 (number 1) Submitted by: Soul Body Gems Date completed: 8-8-2024 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. 0.94 ct. Fig. 2: Backscattered electron image of an area of the specimen. Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (plagioclase, labradorite compositional range) Summary of findings: This specimen (Fig. 1) is a beautiful cut stone. Compositionally, it is an intermediate plagioclase, a labradorite (Figs. 2 and 3). The density was measured as 2.71 g/cm3 and the refractive index measured on the table is around 1.57, both are in agreement with labradorite. Date: August 8, 2024. Signature.
Additional variation: tested bracelet beads
Sample 1104, completed November 1, 2024, examined approximately 4.5 mm beads from a bracelet. These beads are plagioclase rather than potassium feldspar. Unlike the earlier faceted labradorite specimen, the analyst places these beads likely in the andesine–oligoclase compositional range because they contain less calcium.
The report attributes the schiller to a thin, sodium-rich albite film formed through exsolution. The two reports therefore document different plagioclase compositions sold under related moonstone trade names; they should not be treated as identical mineral identifications.
View the original test results — sample 1104
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.
Read the complete report as text
Analytical Result Report
Sample id: 1104 (blue bead bracelet #6)
Submitted by: Soul Body Gems
Date completed: 11-1-2024
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.
A Bruker D2 Phaser X-ray diffractometer was also used and operated under 30kV and 10 mA.
Fig. 1: Photograph of the specimen. Approximately 4.5 mm maximum dimension of the beads.
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Fig.2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (plagioclase)
Summary of findings: This specimen (Fig. 1) is pretty. The bads are not a potassium feldspar, thus it is not a moonstone but a plagioclase (Figs. 2 and 3). This plagioclase is not that calcium-rich to make it a labradorite, it is likely in the range of andesine-oligoclase, thus it is more sodium-rich. The schiller is due to exsolution of a thin, albite-rich (sodium-rich)film which causes this pretty optical effect.
Date: 11-1-2024 Signature
