I adore highly saturated blues that still provide some shading. What do you think is the MOST saturated blue on the market? Does not need to be waterproof or bulletproof.

I truly enjoy Private Reserve DC Super Show Blue, I add water for shading.

Noodler's Bay State Blue, but it has staining issues as you can see on this forum; I love the colour, though.

Aurora

PR DCSSB
PR LPB

Parker Penman Sapphire
Noodlers Baystate Blue

Baystate Blue is the most vibrant blue I have, and it is definitely saturated.

I've heard Baystate Blue can clog and even destroy pens. Any experience with that?

Neither the Lamy nor the MB Noblesse Oblige I put BSB in were damaged. The clear barrel holding the ink did stain, however, and I'm not sure that it will come off, but the pen itself is fine.

I've had BSB in a Lamy Safari for a couple of months now. No problems, though I don't stick it in the bottle to fill it, and it's blue anyway.

PR Electric DC Blue

Baystate blue. Just be careful what pen you put it in because it will stain everything. For example the converter I use for this ink is exclusive to this ink. Its permanently stained, but I love the color, nothing beats the blue blue blue of Baystate blue.

Certainly, Levenger Cobalt must be in the running.

What hue of blue are you thinking of? Light blue, medium blue or dark blue?

For light blue, consider Diamine Aqua Blue.

Medium blue, it has to be Bay State Blue or PR Lake Placid Blue.

Dark blue, Parker Penman Sapphire Blue (if you can find some) or DC Supershow Blue.

While BSB color is very bright and gorgeous I never saw any shading with it do you have a pen with which it shows any? I'm curious

I don't know about "most" but all of Private Reserve's Blues are quite highly saturated but still provide considerable shading, especially when diluted a bit (but even when not, especially via an italic nib of some sort). The same is true of Noodler's standard blues (I have no experience with their bulletproof inks); some of the less dark Noodler's Blues, such as Ottoman Azure, provide excellent shading even when not diluted at all. Noodler's controversial bright blue, Baystate Blue, provides no shading at all in my limited experience (used the stuff once, was put off by its feathering and staining properties, and haven't touched it since).

Simon