there is already a state that determines if something has been cured or not. the problem is any particles that are created thereafter would not be immune, and spread to even the things that have been cured, it's a fight between the cured and uncured state just like an infinite sprk loop.
there must be a state somewhere that determines that dmnd cant have virs passed to it. maybe a way to pass that attribute to other elements would be useful.
ex: make a pot of dmnd, fill it with virs then "set tmp2 virs 93" 93 happens to be the element number of bcln, from there drop 1px of soap so that it turns into bcln(virs) and you can drop virs onto the bcln without it getting infected. this works with any kind of solid so long as you have a constant supply of virs that it "remembers" its immune to.