GEM KNOWLEDGE · LABORATORY NOTES
Labradorite (Yellow)
Two faceted yellow stones were examined. Both are plagioclase with a composition in the labradorite range.
Tested specimens: Sample 1205 (#4 yellow labradorite), 5.23 ct and 3.89 ct · Report completed: January 12, 2025.
Key finding: Both tested as labradorite, not glass. Their crystalline, monocrystalline appearance was considered consistent with natural stones. Iron at approximately 0.4–0.6% is likely responsible for the yellow hue.
What was established
The report examined both cut stones by electron microscopy and XRF, with polarized-light examination of the smaller stone. It describes them as appearing natural; that phrasing is an observation, not a comprehensive origin or treatment certificate. The analysis applies to these two stones.
View the original test results
Select either page to enlarge the report.
The two directory names share this report. Please credit Soul Body Gems, Alexander Falster, and the Maine Mineral & Gem Museum when referring to these results.
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.
-
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 smaller specimen.
-
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. (labradorite)
-
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. 4: Energy dispersive spectrum from the larger stone in Fig. 1. (labradorite).
Read the report findings as text
Sample 1205 (#4 yellow labradorite), completed January 12, 2025. The 5.23 ct and 3.89 ct faceted stones are plagioclase, compositionally labradorite. Both are crystalline and monocrystalline, rather than glass, and appear natural. The researcher suggests iron at 0.4–0.6% likely causes the yellow color.
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: 1205 (#4 yellow labradorite)
Submitted by: Soul Body Gems
Date completed: 1-12-2025
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 specimens. 5.23 and 3.89 cts.
Fig.2: Backscattered electron image of an area of the smaller specimen.
Fig. 3: Energy dispersive spectrum of spot 1 in Fig. 2. (labradorite)
Fig. 4: Energy dispersive spectrum from the larger stone in Fig. 1. (labradorite).
Fig. 5: The smaller specimen in polarized light.
Summary of findings: These specimens (Fig. 1) are beautiful cut stones. Both are plagioclases, compositionally labradorite 9Figs. 2-4). The are crystalline and thus are not glass, monocrystalline and appear natural (Fig. 5). A small iron content of 0.4-0.6 % is likely responsible for the yellow hue.
Date: 1-12-2025 Signature
