Caitlin - I saw the laTendresse (?) coin pearls as part of the display/education material held by the GIA lab in their HK office - not anywhere for sale. They weren't spectacular, but as happened throughout the whole GIA course, it was inferred that their production was a significant part of CFW stock around the world. (Sorry, I digress).
The pearl in the pic looks like a chinese one to me, I only thought of the American connection given the question earlier by Dave as to whether the american pearl co had ever produced coin pearls.
Dave - I am sure the Latendresse coins would be nucleated.