I think they’ve added it to the notebooks only so you can easily keep track of their count.
In case someone wants to know the origin of those specks of dust: Some guy on Twitter wanted to pay Ron money to get an in-game item, no matter how insignificant it is. Sadly he deleted his account so this conversation is lost.
https://twitter.com/grumpygamer/status/754341458614693889
https://twitter.com/grumpygamer/status/754356443294359552
https://twitter.com/grumpygamer/status/754376317768900609