"According to Sakura’s history, Sakura invented gel-based ink. The Sakura
Gelly Roll is another $1 gel-based ink pen that is fade proof, water proof, and
acid free. It is an archival quality pen. Unfortunately it is not as easily
found as the Pilot G2s, one of the reasons I do not rate it as highly as the G2.
Many writers prefer the Sakura to the G2, however, and for the low price tag, it
is worth trying out if one finds it in an art supply store.
is not meant to be refilled but at $1 each, it wouldn’t be worth selling
separate ink refills anyway. The ink inside the Sakura cannot be used inside
other roller ball pens.
over a dollar each plus shipping which gets quite costly for a pen. If you are
really not happy with a G2 and want to try another cheap pen, the Sakura is
worth looking into."