Pareltje- Hi there. I'm not surprised by the link sadly. I can't ever recall JP Kasumi pearls looking like that. There is a lot of cannibalization of pearls between Etsy and Ebay.
The vendor that prompted this thread seems to have a "template" and continually lists obvious dyed black freshwater pearls as Vintage tahitians...which is as laughable as it is dishonest, if they were trying to pass them off as Akoya that would be more worrisome, but either way they are not interested in truth, I say that due to their replies to me when I've tried to explain their pearls are NOT Tahitians. I am not out to give anyone a bad reputation so I won't post their smug replies. At the time I was hoping the PG pearl police would jump in. To this date the vendor still lists this way, I've given up.
I just don't know who is truly misinformed and who is just out to rip people off. I go by the facts, the ripoff artist dips and dodges or ignores altogether, the misinformed takes the time to update their listings when put on notice, thats all I will say.