Golden sheen sapphire, (or goldsheen sapphire) is a recently discovered 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.
Goldsheen sapphire has a golden shine, almost like gold. Translucent blue, green or yellow material is sometimes present together with the gold.Journal of Gemmology. volume 35 no.5 https://gem-a.com/component/k2/volume/volume-35-no-5-2017-2-2 Pages 430-435Journal 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". Particularly prominent is hematite which will often result in the formation of geometric hexagonal patterns within the gemstone crystal.
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). Golden sheen has a stronger golden shine and sometimes has blue and gold in the same stone.
Source
Previously, it was claimed in the Journal of Gemmology (JoG), that the source is a depleted mine in Kenya close to the border of Somalia. TJN Colors, GIT and In Color 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.Unninayar, Cynthia; "Gold Sheen Sapphires – From Gold Mine to Market" (2018) (https://gemstone.org/incolor/38/92/ ). In Color: Summer 2018, Pages 92-95."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. also previously published that the origin was Kenya. However, GIA Tokyo and Gems and Jewellery stated in 2018 that the location is not known. GIA 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. and JoG stated that golden sheen sapphires are reportedly mined in northeastern Kenya, there is no other published chemical data available from this region
References