[perlas]

This is the only relation I see in nacre thickness and luster --- the bead nucleus maybe seen in thin-nacred pearls. And since a thin nacre is translucent/transparent, the pearl may have a chalky appearance.

On the other hand, I've smashed a chalky south sea with good nacre thickness!

A lot of written resources always say good luster is indicative of thick nacre.

However, if we think of good nacre quality/structure, maybe a thin-nacred pearl is possible to have great luster even without treatment. Doesn't great luster hide blemishes? Why can it hide a nucleus?

Also, as I've seen in fwps, in some pearls (they're usually in the multi-colored strands), there can be that mirror-like shine when placed in incandescent/ pearl lights.. they can have that metallic mirror shine (but in daylight, you can see some depth unlike in overly treated and fake pearls).