_Those are kinda sizable. Are they your pearls or has someone come to ask your opinion about the cracks?
I have some old akoyas that now have cracks like that, but the cracks are my own fault. I wore them every day for over 10 years, and I bought them used/old from an antique shop, in good shape but not superb, dulled by dirt, but
no cracks until...
Anyway here's the story - there was a thread on Pearl Guide way back when about restoring yellowed pearls to white again. I tried most of the remedies. One suggested that rehydrating them in the sun was a good idea. The sun warmed the water, and they did look a little better...I took the idea too far, figuring that warmer water = warmer nacre, which would rehydrate faster. I put them in warmer and warmer water until unfortunately, the last time I looked some were cracked.
The nacre expanded more successfully than the bead? or is the bead intact and some of the innermost nacre cracked? At least the surface layer of nacre expanded and contracted without a crack.
1)Not one of my cracked beads has a surface crack, and
2)size of the bead doesn't matter and
3)the cracks are 2 yrs old and haven't spread to the surface. So, that's my result after 2 yrs - but what does it matter since the appearance is unsightly whether or not the crack progresses? Well, any increase in knowledge is of benefit, of course.
I think impact as a cause would show a crack through the outermost layer of nacre. There are a few PGers who've broken pearls deliberately - I hope one of them will take up the thread here, but
- if someone doesn't the topic has probably been addressed in one of the threads on the forums.
I'm going to leave here and check through the archives, but for now you know at least one cause - hot water, no matter how slowly you heat it up.
I'll be checking on the damage that sonic cleaners do next.
In the meantime, though this is very tardy
"Welcome to Pearl Guide!", and I hope you've stuck around in spite of the topic not having been taken up. There's a world of knowledge here, and really good people.
Hey, you're already a pearl-guy! and probably already know this stuff! Dang! Don't I feel stupid.
Well, at least you're still here, right? and posting, etc...and you can do your own checking!