Next site is the history of pearl divers.
Next is a maps of MIKIMOTO PEARL ISLAND.
Next site is demos time and season.
Next is total information.
Jerome, I went to see them several years ago in June, but the program I did involved going to their hut and eating with them, not watching them do any diving. I'm pretty sure that they still do daily demonstrations of their diving style at Mikomoto Pearl Island in Toba city, but I can't find any information on times on their website. Hope that helps though.
I went to Mikomoto Pearl Island in Toba earlier this year. They do diving demos at least once an hour, but you are watching from an above water viewing deck about 20 metres away, so you can't really see much other than them going under water and coming back with what looks like a handful of seaweed which they proudly hold into the air. Having said that the museum on cultured pearl making and memorial museum for the founder of Mikimoto Pearl are very interesting. Look out for flyers are nearby locations to get a coupon with a few hundred yen off the entry price.