The green certificates are issued only  in the 12th grade. These certificates have been specially designed to contain the highest security features available to eliminate the possibility of forgery. 

Sold in packs of 100.
Each certificate is printed on watermark paper.  By holding the certificate to the light, the mark can be verified.  The paper is also resistant to written tampering.  In the event that someone tries to change the name of the student, signature or date.