@genius2737
Consider that Crystal is a reservoir of energy or Serum that you charge it with using VK.
The user of crystal will draw energy from it. So energy will get used up.
Nobody can predict how much time the energy will remain in crystal beacuse it depends in the need of the person using it.
If you practise VK healing regularly, you may be able to sense.
Or else keep charging it daily
You cannot charge things that are used as a reservoir with NOW FOREVER because energy is getting used up.
Check VK BASIC POST 13 to know about intention NOW FOREVET.