concessional certificates

Harish Chand Saini (226 Points)

11 April 2019  
our customer has provide a certificate issued by dsir on dt August 2016 validity till2021.
The coustomer said that this certificate is valid in GST regime and we can purchase on concessional rate @ 5%.

Is the same is valid in Gst? If any notification in this regard then pl. tell me.