What’s going on with this two-toned pearl?

[triscodiscuit]

Looking at a string of these vintage irregular pearls and this blue and gray one has me curious as to how this happened?

 

[Pearl Dreams]

Bad dye job?

 

[Lagoon Island Pearls]

Bad dye job?

Either a weak dye with a harsh solvent or perhaps poorly irradiated. Either way it's a bad attempt making bad pearls better resulting worse instead.

 

[CortezPearls]

Yes, bad dye job!