Actually black ink is a traditional ingredient in chinese medicine and many instick recipes also include medicinal ingredients. The most expensive Old Hu Kai Wen ink per gram is 药墨 Yao Mo Pearl Medicine Black Inkstick:
At under $15USD it’s not the most expensive inkstick in the collection but at 2.7 grams it is the most expensive per gram. It’s a black carbon based ink which includes pearl and other precious and medicinal ingredients and is covered with gold powder. Follow the link above to read more about it or read the article on historic ink recipes.
Inkston are not scientists or doctors and our notes are for cultural and historic interest only, not medical advice.
We don’t advise eating ink. Especially mineral colours such as Vermillion, Realgar, Orpiment Red/Orange/Yellow colours which are traditionally made from Mercury and Arsenic sulphides.