Before he went full - time on gem testing lab work and instructor , he was an experienced gem dealer and doing wholesale and retail jewellery business .
Tay Thye Sun has been practicing gemology after he graduated from the Gemological Institute of America since 1980 .
Before Tay Thye Sun went full - time on gem testing lab work and instructor , Tay Thye Sun was an experienced Tay Thye Sun   and doing wholesale and retail jewellery business .
Tay Thye Sun has been practicing gemology after he graduated from the Gemological Institute of America since 1980 .