I just got a shipment of birthday inks in from Swisherpens, with Yard-O-Led blue, Noodlers green marine, and PR plum.
The Yard-O-Led blue has the word "blue" on the box and bottle, but is sold as "royal blue" by Swisherpens. In either case, it's supposed to be the same ink as Diamine royal blue.
I tried it last night and was a little underwhelmed. This morning though I gave it another look and - wow - the color really popped out. Maybe this is an ink that just doesn't look as good under flourescent lighting, or maybe my subconscious worked on me over night, but this is my new favorite blue ink.
I would describe it as a vibrant blue, darker than Diamine Tropical Blue, but without a hint of violet or gray, with a medium flow and shading.
Stephen