Just whip up a plain pearl and use a toothpick dipped in blue colorant and stir it in a tiny bit at a time until you have the blue as dense as you want it. You may try the same with a very small amount of white too to add some opaqueness to it. Or you can get the lurecraft stuff. I like the toothpick method because I can adjust the color or even use a different color.
Instead of the regular blue, I'd give the fluorescent blue a try first. You can always bring it down a notch using a dab of plain blue.