Realistically, it could depend on the renderer. Having said that, LDView uses 50% alpha for "transparent" colors. I also completely disable back-face-culling for transparent colors, and (by default) depth sort them. This means that generally any pixel with transparent geometry in it will in fact have at least two layers of transparency (front and back surface) drawn over whatever happens to be behind that. If you don't disable back-face-culling for transparent parts, you'll probably need to make them more opaque.
LDConfig colors can contain an actual alpha value, and LDView respects that. (I think, for example, glow-in-the-dark is mostly opaque, but not quite.)
LDConfig colors can contain an actual alpha value, and LDView respects that. (I think, for example, glow-in-the-dark is mostly opaque, but not quite.)