Actually there are a zillion things that can result in diamond pics looking different.
The only way to fairy compare the appearance of two diamonds is to place them both side by side under a camera and take one single pic of the pair of them.
Even then, one might be closer to the UV light source than the other - rendering the comparison inaccurate.
In the comparison videos I did my best to reproduce the same light conditions and filmed in the exact same location but still... so many variables!!!