GEM KNOWLEDGE · LABORATORY NOTES
Ruby
Ruby is the red gem variety of corundum. This overview will grow as we add more background, photographs, and tested material.
Several different mixed-mineral pieces in our archive contain corundum, but they are not interchangeable examples. The reports identify minerals in the individual specimens; neither report alone grades the corundum grains as faceted ruby gems.
Variation 1 · “Power Ruby” obelisk
In sample 9047, the lab found small corundum grains within a predominantly serpentine-group matrix. No smoky quartz was identified. Read this specimen’s full findings and transcript →
The three pages of the Power Ruby report:
Variation 2 · Ruby Kyanite from India
In sample 92855 (#10), the bulk is kyanite and red grains include chromium-bearing corundum. The report also records chromian muscovite and a likely titanium oxide. Read the Ruby Kyanite findings and transcript →
The five pages of the Ruby Kyanite report:
These are distinct tested mineral associations; similar market names do not establish identical composition.
Variation 3 · Ruby Clinochlore
The April 20, 2022 specimen with printed sample ID 92905 contains corundum, likely clinochlore, spinel and accessory minerals. Read the Ruby Clinochlore findings →
Select a page to enlarge it. 5 pages; findings are summarized in accessible text above.
Variation 4 · Kyanite Ruby Clinochlore from China
The August 16, 2022 disk with printed sample ID 92937 contains XRD-confirmed kyanite, corundum/ruby, chlorite-group material and muscovite. Read the Chinese disk findings →
Select a page to enlarge it. 6 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. 1: Backscattered electron image (carved opal). This is in the pink area
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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. 2: Energy dispersive spectrum of spot 1 in Fig. 1. (amesite, serpentine group).
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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. 3: Backscattered electron image (obelisk). This is in the brown area.
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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. 4: Energy dispersive spectrum of spot 1 in Fig. 3. (amesit, serpentine groupe).
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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. 5: Energy dispersive spectrum of spot 2 in Fig. 3. (corundum).
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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. 6: Energy dispersive spectrum of spot 1 in Fig. 3. (antigorite).
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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 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 spectral analysis of spot 1 in Fig. 2. (Ti oxide such as rutile)
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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. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2. (muscovite, chromian)
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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. 5: Energy dispersive spectral analysis of spot 3 in Fig. 2. (aluminum silicate – kyanite)
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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. 6: Backscattered electron image of another 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. 7: Energy dispersive spectral analysis of spot 1 in Fig. 6. (corundum)
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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. 8: X-ray maps of the area shown in Fig. 2: Silicon: green, aluminum: red, titanium: blue.
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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 spectral analysis of spot 1 in Fig. 2 (chlorite group)
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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. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2 (high magnesium pyroxene/amphibole)
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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. 5: Backscattered electron image of another 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. 6: Energy dispersive spectral analysis of spot 1 in Fig. 5 (zircon)
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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. 7: Energy dispersive spectral analysis of spot 2 in Fig. 5 (corundum).
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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. 8: Energy dispersive spectral analysis of spot 3 in Fig. 5 (spinel).
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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. 8: X-ray maps showing mganesium in red, aluminum in green and silicon in blue.
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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 (chlorite group species)
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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. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2 (aluminum silicate)
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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. 5: Energy dispersive spectral analysis of spot 3 in Fig. 2 (muscovite)
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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. 6: Energy dispersive spectral analysis of spot 5 in Fig. 2 (zircon)
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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. 7: Backscattered electron image of another 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. 8: Energy dispersive spectral analysis of spot 6 in Fig. 2 (muscovite)
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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. 9: Backscattered electron image of another area of the specimen. Dark object on top is a marker arrow.
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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. 10: Energy dispersive spectral analysis of spot 1 in Fig. 9 (corundum/ruby).
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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. 11: X-ray map of the area shown in Fig. 9. Aluminum: yellow, magnesium: red, silicon: green.
Read the Power Ruby obelisk laboratory report as text
Analytical Result Report Sample id: 9047 (pink and brown obelisk) Submitted by: K.Bitner Date submitted: June 4, 2020 Date completed: June 5, 2020 Operating conditions: JEOL JSM-6400 operated at 25 kV acceleration potential, 15 mm working distance, 15 degrees sample tilt, coated with 250 Å carbon. Using the X-ray fluorescence attachment with 35kv potental in conjunction with the EDS system. Fig. 1: Backscattered electron image (carved opal). This is in the pink area Fig. 2: Energy dispersive spectrum of spot 1 in Fig. 1. (amesite, serpentine group). Fig. 3: Backscattered electron image (obelisk). This is in the brown area. Fig. 4: Energy dispersive spectrum of spot 1 in Fig. 3. (amesit, serpentine groupe). Fig. 5: Energy dispersive spectrum of spot 2 in Fig. 3. (corundum). Fig. 6: Energy dispersive spectrum of spot 1 in Fig. 3. (antigorite). Table 1: Trace elements by X-ray fluorescence. element | pink area, ppm | brown area, ppm Fe | 1328 | 2148 Ti | 860 | 7200 Mn | 35 | 60 Summary of findings: This is an interesting specimen! The material is largely composed of serpentine group minerals. Amesite is dominant (Figs. 1-4). Some grains of corundum (Figs. 4 and 5) were note and they have antigorite (Figs 4 and 6) radiating from it, suggesting a reaction. The brown area is much more enriched in iron and titanium than the pink area. The pink is likely caused by a little trivalent iron whereas the brown is likely caused by the much higher content of trivalent iron, possibly coupled with titanium (Table 1). Date: June 5 ,2020 Signature
Read the Ruby Kyanite from India laboratory report as text
This text is transcribed from the laboratory report so the findings and figure captions can be read without opening the page images. The images remain available above for visual details.
Laboratory report
Analytical Result Report Sample id: 92855 (#10) Submitted by: K. Bitner Date submitted: Feb. 14, 2022. Date completed: March 9, 2022. 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. Fig. 1: Photograph of the specimen. 9 cm maximum dimensions. Fig. 2: Backscattered electron image of the specimen. Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2. (Ti oxide such as rutile) Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2. (muscovite, chromian) Fig. 5: Energy dispersive spectral analysis of spot 3 in Fig. 2. (aluminum silicate – kyanite) Fig. 6: Backscattered electron image of another area of the specimen. Fig. 7: Energy dispersive spectral analysis of spot 1 in Fig. 6. (corundum) Fig. 8: X-ray maps of the area shown in Fig. 2: Silicon: green, aluminum: red, titanium: blue. Fig. 9: image under ultraviolet light showing red fluorescence of the corundum. Table 1: Minor and trace element composition of the specimen. (in wt. %). Calcium 0.14 Chromium 0.22 Iron 0.16 Magnesium 0.13 Manganese 0.02 Phosphorus 0.01 Sodium 0.19 Titanium 1.15 Summary of findings: This specimen (Fig. 1) is composed mainly of kyanite (Figs. 2 and 5), corundum (Figs. 6 and 7) and some muscovite. (Figs. 2 and 4) and a titanium oxide species, likely rutile (Figs 2 and 3). The muscovite is chromium- bearing and frequently called ’fuchsite’). The assemblage with kyanite indicates high pressure and low to medium temperature during metamorphism. Continent-continent collisional margins would be a good source of material like this. The X-ray map (Fig. 8) shows the distribution of the main elements clearly. The bulk material is kyanite. The corundum is UV fluorescent (Fig. 9) which is caused by a small amount of chromium which is present in the material (Table 1). Date: March 5, 2022 Signature
Read the Ruby Clinochlore 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: 92905 (#5) ‘Ruby
Submitted by: K. Bitner
Date submitted: April 4, 2022.
Date completed: April 20, 2022.
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.
Fig. 1: Photograph of the specimen. 7 cm maximum dimensions.
Fig. 2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2 (chlorite group)
Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2 (high magnesium pyroxene/amphibole)
Fig. 5: Backscattered electron image of another area of the specimen.
Fig. 6: Energy dispersive spectral analysis of spot 1 in Fig. 5 (zircon)
Fig. 7: Energy dispersive spectral analysis of spot 2 in Fig. 5 (corundum).
Fig. 8: Energy dispersive spectral analysis of spot 3 in Fig. 5 (spinel).
Fig. 8: X-ray maps showing mganesium in red, aluminum in green and silicon in blue.
Table 1: Minor and trace element composition of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Chromium | 0.22 |
| Iron | 0.08 |
| Titanium | 0.88 |
| Vanadium | 0.13 |
Summary of findings: This specimen (Fig. 1) is very interesting! It is composed of a number of mineral species: a chlorite group member, likely clinochlore (Figs. 2 and 4), spinel (Figs. 5 and 8), corundum (Figs. 5 and 7), a magnesium-rich pyroxene or amphibole (enstatite or anthophyllite) (Figs. 2 and 4), the presence of aluminum indicates possibly anthophyllite would be the best fit, and minor zircon. (Figs. 5 and 6). The whole assemblage is highly aluminum and magnesium enriched and suggests a source in a metamorphic environment with a protolith of mixed pelitic , ultramafic or possibly carbonate rocks. Under these conditions, phlogopite would be an expected mineral but it was not found in the areas investigated.
Date: April 20, 2022 Signature
Read the Kyanite Ruby Clinochlore from China 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: 92937 (#8, ruby/kyanite disk)
Submitted by: K. Bitner
Date submitted: July 14, 2022.
Date completed: August 16, 2022.
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 D2 Phaser X-ray diffractometer was used and operated at 30 kV and 10 mA.
Fig. 1: Photograph of the specimen. Approximately 12 cm maximum dimensions.
Fig. 2: Backscattered electron image of an area of the specimen.
Fig. 3: Energy dispersive spectral analysis of spot 1 in Fig. 2 (chlorite group species)
Fig. 4: Energy dispersive spectral analysis of spot 2 in Fig. 2 (aluminum silicate)
Fig. 5: Energy dispersive spectral analysis of spot 3 in Fig. 2 (muscovite)
Fig. 6: Energy dispersive spectral analysis of spot 5 in Fig. 2 (zircon)
Fig. 7: Backscattered electron image of another area of the specimen.
Fig. 8: Energy dispersive spectral analysis of spot 6 in Fig. 2 (muscovite)
Fig. 9: Backscattered electron image of another area of the specimen. Dark object on top is a marker arrow.
Fig. 10: Energy dispersive spectral analysis of spot 1 in Fig. 9 (corundum/ruby).
Fig. 11: X-ray map of the area shown in Fig. 9. Aluminum: yellow, magnesium: red, silicon: green.
Fig. 12: UV-light photograph, ruby fluoresces red.
Table 1: Minor and trace element composition of the specimen. (in wt. %).
| Element | Reported value |
|---|---|
| Chromium | 0.15 |
| Iron | 0.6 |
| Magnesium | 7.0 |
| Potassium | 2.1 |
| Titanium | 0.6 |
| Zirconium | 0.1 |
Summary of findings: This specimen (Fig. 1) is composed of chlorite group species such as clinochlore (Figs. 2 and 3), kyanite (confirmed by X-ray diffraction) (Figs. 2 and 4), muscovite (Figs. 2,5,7, and 8), corundum/ruby 9Figs. 9-11 )and zircon(Figs. 2 and 6). Some apatite is also present. Some of the kyanite is partially replaced by muscovite but some is still left which was revealed by XRD.
The corundum/ruby fluoresces the typical red (Fig. 12).
A very interesting specimen!
Date: Aug. 16, 2022 Signature