TITLE: Good chalk in the UK
QUESTION [11 upvotes]: Sometime ago it was asked in Mathoverflow about good chalk in the US Where to buy premium white chalk in the U.S., like they have at RIMS?. I will be grateful for any recommendations on good chalk in the UK and where to get it.

REPLY [2 votes]: I was recently pointed to this site for buying Japanese chalk (white and color, Rikagaku brand), as well as other Japanese pens and office supplies.
http://www.jetpens.com/
They will ship internationally, though the shipping looks rather expensive.