Wands which use potions will always reset their colour to white. The formats I've tried are:

  icon: potion:A83232
  
  icon: potion:#A83232

And neither work (with any hex colour) and are simply set to white. However, there is a strange bug to be noted-
When using the second format shown, and using 'spawnitem' the wand will spawn the correct defined colour, but is again set to white once picked up.
You briefly discussed and tried to fix this problem in February this year after KingofAnomaly#8697 reported it in discord, but the fix seems to have not worked, or perhaps broke again? Just thought I'd give a heads up!