Rainbow moonstone has a very blue (lighter blue) coloring through it and is more transparent. The stone in your pendant is definitely labradorite, in my opinion. The cross-hatching in the stone is typical of labradorite and so is the darker, intense blue color. You got a very nice piece of it. Rainbow moonstone is my favorite stone, so I'm really familiar with it and have several pieces. Labradorite is a close cousin but usually isn't as transparent and has a more intense color with more cross-hatching that looks like cracks. It's a very pretty pendant!