Welcome to my review of Herbin Éclat de Saphir! This is one of my favorite inks. It's a very popular blue ink, widely accepted as one of the nicer blues among the fountain pen enthusiasts. It's one of the more saturated Herbin inks, with nice flow and better-than-average permanence. I took some nice pictures and will let them speak for themselves. ;)
I tested with three pens, a 1.5mm Pelikan Script Calligraphy Pen, my own Goulet fine nib pen (why not?), and a J. Herbin glass pen. These 3 pens all write very differently and show the variation in shading.
'Watercolor' picture, using a q-tip to swab the ink (and a J. Herbin Creapen to draw the outline) on a Clairefontaine Grafit sketchpad.