Hi Pinkjewel,
It really is just a numbers game for
those really special pearls. Vietnamese pearls tend to have more blues and other colors than akoya grown in Japan and China, although you still can find them. Those particular pearls were in the shell for three full seasons, according to the farmer. He said he wouldn't try it again because the attrition rate was just too high in the third year. Those pearls in the blog post were the full collection of special ones he had brought to the show. Hisano is good friends with his daughters, which is why we were able to buy them.
In 2007, while I was acting as tour guide for the GIA Pearls Course writer in China, we were in a processing factory that had just brought in a harvest. There was a big metal bowl filled with baroque blue and silver pearls. To the processor, they were basically rejects. Don't get me wrong, a lot of them were with almost see-through parts to the nacre. But some of them were amazing. I put together a strand of them and showed them off here on the forum. As far as I know, nobody had seen these before. The Japanese had always culled them, maintaining the image that akoya are round, white and perfect.
The link below is the first one from 2007.
https://www.pearl-guide.com/forum/showthread.php?t=1498
This is a photo I took of the bowl.
http://www.flickr.com/photos/pearlparadise/3415913020/in/set-72157616305197053
Now you see them at the shows ranging in price from around $50 to $100 per strand (for a quality you really should avoid because they will peel) to more than $1000 per strand for really special ones.