Didn't the RSS James Cook find a bunch of diamonds where the mantle is exposed beneath the Atlantic back in 2007?

I remember following this as an amateur geologist but never heard anything more after the diary entry found here...

http://www.classroomatsea.net/JC007/diary/diary_12-04.html

I assumed this would have a significant effect on the supply since they indicated that they got over 150 carats simply by dragging a bucket across the sea floor.