Here are the reviews from Tom Mullane, (Old Griz), a well respected member of the FPN:

Colfer's Imperial Inks - Review - Part I

Colfer's Imperial Inks - Review - Part II

"All tests have been 100%!  The double blind test from the calligraphy class received raved reviews; the class loved the ink and I love it too. All in all, I have been very impressed." - James Rouse, VP, Bertram's Ink Well