This is just a quick comparison of three Noodlers' Blues which I recently received samples of. They include Navajo Turquoise, Luxury Blue and Ottoman Azure. Of the three, I was most impressed with the Ottoman Azure which is currently loaded in my TWSBI 530 and got plenty of use today at the office. The Azure, to me, falls right in between turquoise and blue-black and that was what I was looking for in a "medium blue." The Noodler's Blue and Blue Eel were also nice and very similar to the Azure, but I found the Blue too dry and the Blue Eel too wet. The Azure was just right. I was also very impressed with Noodler's Navy.