Bram - You can contact Hanneman Gemological Instruments directly at
P.O. Box 942; Poulsbo, WA 98370. Phone: 360-598-4862. This info is
from the 2002 Lapidary Journal Buyers’ Guide.
Briefly, Dr. Hanneman introduced the Jeweler's Eye to the gem
community in the 1970s. It is his own creation, using a "new"
concept in optics, which he refers to (I’m remembering here)
“relative reflectivity”. There was a lot of brouhaha at the time,
and some unfortunate interactions by folks from places like GIA.
However, Hanneman’s concept, and the Jeweler’s Eye were vindicated,
and it seems a good instrument to have.
Hope that this gives you the access you need.
Jim Small Small Wonders