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To add that the nacre somehow survived the 1500ºF heat of the pyroclastic gases. The woman must have wrapped her body around the earrings as though they were her child. For perspective (and understanding of the woman's priorities): "Roman general (and later emperor) Vitellius was said to have...

The pearls are in remarkable condition! Perhaps just a little rub with Pearl Paradise microfiber cloth…

Simple candling will do. Here from the same paper. I think Krzemnicki was just going after the gullibility of the buyer at a time when purported Melo Melo pearls of large size were becoming unusually common. Such ease of detection would serve to reinforce the advantages of porcelaneous vs...

Tempting to think best to just stay away from iridescent pearls in the modern age of non-bead culturing. But in review of the options, take a look at this 'melo pearl’ as imaged by Michael Krzemnicki of SSEF ("Fake Pearls Made from Tridacna gigas Shells Michael S. Krzemnicki and Laurent E...

If you do decide to watch, it would be interesting to know if they fall in line with the gemmological sector in declaring porcelainous 'concretions' from conch, clam, cassis, scallop, melo melo, etc. as 'not true pearls.'

We can expand the net to include all popular pearl literature, Strack serving a symbolic function. Thus the "burden" I most recently referenced. That's a lot of re-writing to do! But we've made considerable noise here. Someone must be hearing! In all of the referenced papers here I can only...

The Arabic naqur (mollusk shell) is turning out to be a prescient etymology. It would be of great interest to know if you would offer any guidance for Elizabeth Strack on a future update to her comments on nacre. She's one of the most open-minded gemologists I've had the pleasure of meeting!

Should this contain a link?

The nacreous and porcelainous microstructures co-exist within the same shell but preserve their distinct morphologies.

We have discussed "burdens" previously, above. Here I argue that the "common knowledge" being changed (burdened?) is the predominant concept of nacre as the miraculously iridescent 5% organic microstructure with which we are all familiar. Without a more generic overarching term for the...

I like it. I also see that the bulk of the cited research post-dates my time at the SEM in Granada, 2011-2013. It still seems a stretch to apply the term 'nacre', so broadly. Neither do you see such reference in the literature. You would be better than me at finding a more generic term for the...

The equivalencies you are drawing make common usage of the term 'nacreous' as obsolete as the term 'non-nacreous.' Who's going to rewrite the book?

If there is anything in the scientific literature that concisely and transparently defines nacre in such a manner I would want to be the first to see it.

At this point we must agree to disagree. I will be sticking with the terraced/columnar organic secretion models that result in iridescent phenomenon. But will happily campaign for the true-pearl status of 'porcelanous/porcellanous/porcelainous' specimens.

OK so per Douglas' suggestion above, what would be the percentage? The aragonite platelet model of nacre would be differentiated by its organic component. If only our unidentified porcelainous pearls had such a layer!

Yes the low organic component of crossed-lamellar shell material has frustrated all our attempts at genetic extraction for pearl species confirmation. But the issue of 'degree of nacreousness' is still eluding us. What percentage should be assigned to crossed-lamellar shell material, assuming...

This is a very helpful observation. It is still not clear how we can speak of percentages or degrees of nacreousnous. Whether expressing as iridescence or not, nacre is nonetheless nacre. "It either is, or isn't, nacre." My conclusion here is that a crossed-lamellar pearl such as Conch that is...

Are these percentages / degrees of nacreousness referring to the distribution of microstructures throughout the different regions and layers of a shell? If not, can we clarify how nacre, crossed lamellar, prismatic, etc can be secreted together as a homogenous amalgam?

Once again we are dealing with ambiguity that defies understanding. Terraced or columnar aragonite platelets, carefully organized and secreted by the mantle, comprise nacre. It either is, or isn't, nacre. Crossed-lamellar is the anti-nacre, perhaps even the prototypical 'porcelainous'...

I am continuing to have difficulty with the ambiguity. "Highly Nacreous" suggests that there are degrees of nacreous expression, such as "Moderately" or (dare I say) "Non." Aragonite tablets/platelets arranged in terraced (Bivalvia, Cephalopoda) and columnar (Gastropoda, Cephalopoda) forms...