I saw a necklace of keshi (or is it keishi?) pearls today, nuggets of about 5-6mm. They were white but with a rainbow play of colors across them. My Freshadamas have a subtle play of colors (which is lovely!), but this was something different - a vibrant play of colors very easily observable from a distance. I've never seen colors like that on a round pearl, though I'm sure Zeide has some in her collection!
Someone mentioned that bleaching has a negative effect on orient - does that account for the difference? Or are there other factors (e.g., the shape, the host, maybe even color treatment)?