Golden sheen sapphire

Golden sheen sapphire, (or goldsheen sapphire) is a variety of corundum. Goldsheen sapphire has been tested and confirmed in lab reports as "natural sapphire" by GIA, GIT, GRS, AIGS, Tokio gem labs and Lotus.

Gold/Golden Sheen Sapphire
General
CategoryOxide mineral
Formula
(repeating unit)		Aluminium oxide, Al2O3
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (32/m)
Space groupR3c
Identification
ColorTypically metallic gold, copper or bronze, blue, green but varies
Crystal habitAs crystals, massive and granular
FractureConchoidal, splintery
Mohs scale hardness9.0
LusterVitreous
Specific gravity3.95–4.03
Optical propertiesAbbe number 72.2
Refractive indexnω=1.768–1.772
nε=1.760–1.763,
Birefringence 0.008
PleochroismStrong
Melting point2,030–2,050 °C
FusibilityInfusible
SolubilityInsoluble
Other characteristicsCoefficient of thermal expansion (5.0–6.6)×10−6/K
relative permittivity at 20 °C
ε = 8.9–11.1 (anisotropic).[1]

Goldsheen sapphire has a golden shine, almost like metal. Translucent blue, green or yellow material is sometimes present together with the gold.[2][3] Particularly prominent is hematite which will often result in the formation of geometric hexagonal patterns within the gemstone crystal.[4]

goldsheen cab

Evidence

Several articles, including the Journal of Gemmology state that gold sheen sapphire is high in iron and titanium oxide. It has inclusions of ilmenite, hematite (gold color) and magnetite (black). It exhibits asterism and hexagonal growth, a lack of UV fluorescence, healed fractures and polysynthetic twinning (parallel lines). Declared as a "new variety" in 2015,[5] goldsheen has a stronger golden shine than other material and sometimes has blue and gold in the same stone.

Source

Previously, it was claimed in the Journal of Gemmology (JoG),[6] that the source is a depleted mine in Kenya close to the border of Somalia. TJN Colors, GIT and In Color [7][8][9] also previously published that the origin was Kenya. However, GIA Tokyo [10] and Gems and Jewellery [11] stated in 2018 that the location is not known. GIA [12] and JoG [13] mention that there is no evidence of gemstone deposits in the flat border region near Somalia. Only two people are known to have acquired Goldsheen Sapphire rough stone. Tanzim Khan purchased the largest amount from an African trader, who agreed not to sell to anyone else. However, Loz Charles also met this African and purchased a smaller amount from him at a later date. The search for the secret mine goes on!

Optical effects

Gold Sheen Sapphire has a subtle effect of color change. This means that the golden surface shines strongly when the light hits it directly. It will also reflect the color of light being shined. What this means is that it will look different under cold white light as compared to more natural soft yellow light.[14]

Mixed colors

Heating and treatment

Golden sheen sapphire is not heated or treated. Testing of heat treatment on sample batches has resulted in diminishment of the gold sheen effect, reducing the appeal of the gemstone.[15]

Use in jewelry

Golden sheen sapphire has been used in jewelry production by companies including:

  • Audley-Charles
  • William Travis Jewelry
  • TVSN Australia
  • David Yurman
  • Cartier
  • John Hardy

Awards

In 2016 a gold sheen sapphire ring by William Travis Jewelry won the American Gem Trade Association Savor Silver Award, Men's Wear.[16]

References
  1. Harman, Alang Kasim; Ninomiya, Susumu; Adachi, Sadao (1994). "Optical constants of sapphire (alpha-Al2O3) single crystals". Journal of Applied Physics. 76 (12): 8032–8036. Bibcode:1994JAP....76.8032H. doi:10.1063/1.357922.
  2. Journal of Gemmology. volume 35 no.5 https://gem-a.com/component/k2/volume/volume-35-no-5-2017-2-2 Pages 430-435
  3. Journal of Gemmology. volume 34 no.8: pages 678–691. Bui T.N., T.N.; Deliousi, K.; Malik T.K., T.K.; De Corte, K. (2015). "From exsolution to 'gold sheen': A new variety of corundum".
  4. Nalin Narudeesombat, Saengthip Saengbuangamlam, Thanapong Lhuaamporn and Thanong Leelawatanasuk (2016). "Golden Sheen and Non-Sheen Sapphires from Kenya" (PDF). The Gem and Jewelry Institute of Thailand (Public Organization), Bangkok, 10500, Thailand. July–August 2016: 282–288.
  5. Bui T.N., T.N.; Deliousi, K.; Malik T.K., T.K.; De Corte, K. (2015). "From exsolution to 'gold sheen': A new variety of corundum". Journal of Gemmology. 34 (8): 678–691.
  6. Bui T.N., T.N.; Deliousi, K.; Malik T.K., T.K.; De Corte, K. (2015). "From exsolution to 'gold sheen': A new variety of corundum". Journal of Gemmology. 34 (8): 678–691.
  7. Wheat, Barbara; “Aesthetic to the core” (2016) (http://www.tnjcolors.com/Issues/V3_I2/V3_I2.html). TJN Colors volume 3, issue 2. Pages 60-61.
  8. Unninayar, Cynthia; "Gold Sheen Sapphires – From Gold Mine to Market" (2018) (https://gemstone.org/incolor/38/92/). In Color: Summer 2018, Pages 92-95.
  9. "Golden Sheen and Non-Sheen Sapphires from Kenya" (https://www.git.or.th/eng/testing_center_en /lab_notes_en/glab_en/2016/11/D5-A0210-1.pdf)(PDF). The Gem and Jewelry Institute of Thailand.
  10. Katsurada, Y; Miura M.; Saruwatari, K. "Golden Sheen Sapphire and Syenite/Monzonite–Hosted Sapphire From Kenya" GIA Tokyo: Gems & Gemology, Fall 2018, Pages 322-323.
  11. Bui T.N. "Shimmering Sapphires" (https://gem-a.com/news-publications/gems-jewellery) Gems and Jewellery: Winter 2018, P36-39.
  12. Katsurada, Y; Miura M.; Saruwatari, K. "Update on trace-element chemical characteristics of golden sheen sapphire." (https://www.gia.edu/gems-gemology/summer-2018-gemnews-update-on-trace-element-chemical-characteristics-of-golden-sheen-sapphire) Spring 2018, Vol. 54, No. 2.
  13. Bui T.N., T.N.; Deliousi, K.; Malik T.K., T.K.; De Corte, K. (2015). "From exsolution to 'gold sheen': A new variety of corundum". Journal of Gemmology. 34 (8): 678–691.
  14. Charles, Loz, "About Goldsheen Sapphire" |url=https://www.goldsheen-sapphires.com/information.html
  15. Charles, Loz, "About Goldsheen Sapphire" |url=https://www.goldsheen-sapphires.com/information.html
  16. "2016 AGTA Spectrum Awards Winners". www.agta.org. Archived from the original on 2016-11-17. Retrieved 2016-12-06.
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