Is there anyway from which we can measure the viscosity of honey using a refractometer?
Theoretically, if refractive index and viscosity are both simply functions of moisture content, you should be able to use one to approximate the other using an empirical standard curve. However, based on this paper, it looks like the relationship between moisture content and viscosity at 25C can vary quite a bit between different types of honey, expecially down below ~18% moisture. So I'd be pretty hesitant to rely on refractive index for acurate viscosity measurements unless you first rigerously validate your methodolgy against empirical viscosity measurements.