Sorry…It seems that I have mixed up the URL’s…
Many thanks for Fred Ward who kindly corrected me…
Here are the right ones…
…
Tips From The Jeweler’s Bench - Update Notice
ADDED
o Basic Optics Notes for Gemology
https://www.ganoksin.com/borisat/nenam/optic.htm
o Notes On Specific Gravity
https://www.ganoksin.com/borisat/nenam/gravity.htm
o The Story of Red Spinel
https://www.ganoksin.com/borisat/nenam/sspinel.htm
Regards
Dr. E. Aspler
Managing Director
Ganoksin Jewelry Co.,Ltd.
aspler@ganoksin.com