Let's think like a photographer.
Proper lighting is essential - white background, strong backlight, fitting HDRi
Shader - Principled BSDF will do (let's keep it simple)
Use post-processing - adjusting midtone contrast, color-corrections
Outer Seed shader:
Roughness - pretty low, it needs to reflect environment and not
Clearcoat - ...
The standard Glass shader gives you exactly that.
Or if you prefer Principled BSDF like me:
Set Transmission to 1
Use Roughness and Transmission roughness to control the glass type
Add thickness to your glass for realistic results
Suzanne on one side, and a black material on the other to make a mirror
To make this work in Eevee
enable Refraction in the ...