Gold Sheen Sapphire Article and Lab Report from GIT

The GIT (The Gem and Jewelry Institute of Thailand) has just completed an excellent lab report on gold sheen sapphire.  They have also featured gold sheen sapphire in the latest GIT magazine.

Gold Sheen Sapphire feature article in GIT Magazine
Gold Sheen Sapphire feature article in GIT Magazine July-August 2016

From the lab report:

GIT Gold Sheen Sapphire report

Golden Sheen and Non-Sheen Sapphires from Kenya
Nalin Narudeesombat, Saengthip Saengbuangamlam, Thanapong Lhuaamporn and
Thanong Leelawatanasuk
The Gem and Jewelry Institute of Thailand (Public Organization), Bangkok, 10500, Thailand
Abstract
A new variety of sapphire from Kenya with unique golden sheen ± star phenomena, the so- called
“Gold Sheen” sapphire has been introduced to the gem market in the last 6-7 years. This study was aimed
at characterizing both the sheen sapphire and non-sheen sapphire from the same locality. It was found that
both sheen and non-sheen samples shared somewhat similar inclusion assemblages, namely magnetite,
goethite, hematite, short needles and zircon. The sheen stones, however, were apparently translucent to
opaque with golden sheen ± star effect caused by the reflection of the light from the combination of dense
and well-oriented reddish brown platelets and short needle-like inclusions exsolved along three
crystallographic directions in the basal pinacoid of sapphire. The transparent-to-semi-transparent nonsheen
stones, in contrast, contained relatively much less amounts of platelets and needles. The advanced
analyses revealed that both sheen and non-sheen sapphires contained high iron content, including boehmite,
diaspore and kaolinite which were good indications of untreated stones.

 

The full report is available here:  http://www.git.or.th/2014/eng/testing_center_en/lab_notes_en/glab_en/2016/11/D5-A0210.pdf

 

Leave a Reply