1. Guild Gem Laboratories, Shenzhen 518020, China
2. School of Gemology, China University of Geosciences, Beijing 100183, China
3. Guild Institute of Gemology, Shenzhen 518020, China
4. Guild Gem Laboratories, Bangkok 10310, Thailand
5. Guangdong Provincial Gem & Precious Metal Testing Center, Guangzhou 510080, China