One thing is for sure especially when it comes to HDMI cables Certified or not - buy it from a place that allows easy returns like local stores and Amazon.
I recently tried a few cables from Amazon that all claimed HDMI 2.0b High-Speed and all that with my new JVC NZ3. Not all of them worked. The BlueRigger cables worked for me so I kept those cables and returned the rest. However, the BlueRigger cables don't work for EVERYONE either. I guess no cables work for everyone.
I've seen reviews on the newer "Premium Certified" HDMI cables on Amazon. I still see some people (like 8% or more) saying that the cables didn't work for them.
So no guarantees even on the so-called "Certified" cables.