Thank you for sharing beautiful experiences of your dad with VK in just 2 months.
Yes you are right, we get results with VK irrespective of its physical properties, because the physical properties are of the raw bangle , even before its attuned with Cosmic energies by Sir.
For roughness, just use a sandpaper. Rub the sand paper on the surfaces of VK, where you know might be causing discomfort to the skin.
This can be done easily. And VK will still have the same healing properties.
In case you don’t have a sand paper, you can mimic its properties, though it would be better to use real sandpaper.