Sailor Blue Ink
The Sailor Blue Ink. Got it for the reddish glow it gives when used in a wet pen. Apart from that special effect, it is a very business like blue. This one is more conservative than Visconti Blue.
See the reddish glow? The effect is subtle in real life, but I exaggerated it by taking the photo at an angle and using strong lighting. Some papers show the effect more prominent. This one is the Moleskine Cahier.