The Granat Turnov Cooperative is registered with the Assay Office and guarantees the authenticity of the precious metals and stones they use. Each garnet gem has to be accompanied with a certificate proving that the jewel is fitted with Czech garnets from deposits in the Czech Republic that are owned by the cooperative. Each garnet gem is also hallmarked by the manufacturing brand of the cooperative, i.e. the letter G. By these attributes the cooperative guarantees the originality and authenticity of the gems with Czech garnets. 

Decorative glass products of the Granat Cooperative are supplied with a certificate that proves that during their manufacture Czech garnets were used

Each team moldavite gem of the Granat Cooperative comes with a certificate demonstrating the use of that original Czech stone.