Different colors...
Well, if you have a look here at
Ymyrlix, I used the pearls on the gold, as well as the blade. It is more obvious on the gold of course, but I found it added a lot of extra depth.
If you look here at
Skoli Warrior you can see the same effect on the gold and silver, but I also went a step further, and mixed up a rusty chestnut colored metal for all the armor plates and such. I also used the pearls on that as well.
I kind of like the effect as it has a very slight metallic sheen all by itself

Of course, I have no other colors of pearls, but I imagine you could just tint the white with inks say, like my rusty metal....