Does anyone know how common Furby's with silver eyes are?

Kind of a random question, but I don't see them super often! I saw some on a gen 8 Blueberry Furby listing a while ago, and I just saw some on a gen 7 Color Change Furby. Pretty cool stuff!

I'm super curious about Furby eyes in general tbh. If you've ever seen a Furby with unique eyes, lmk immediately because I would love to hear about it! :)