Perhaps a bug perhaps forgetful
From Fallen London Wiki
I don't recall ever giving this man the cold shoulder, but lo and behold I obtained this. And rather recently!!! I only realised it when checking my contacts to send letter to.
If it's a bug perhaps it'll clear up and I'll be getting diamonds from him again. Maybe some swap with a different quality or google chrome is being spiteful.
If not, I may just be a silly goose who somehow managed to get this without it registering, and now got the thief rather upset with me, alas.