It'll be great if someone can invent an accurate in-situ low-cost fake honey detector.

For a low tech pure honey detection you can mix a few drops of honey with a warm water then swirl the mixture in a bowl. If you see the appearance of seamless hexagonal pattern appearing like a honeycomb, the honey is said to be pure.

I've used this method many times and mostly works, i.e the hexagonal honeycomb pattern does appear, but the honeycomb pattern probably can appear with fake honey as well. It will be very interesting to test this rudimentary technique with fake honey for accuracy.