DeBeers specifically keeps a tight reign on how many are dispersed to the public so as to keep the price artificially high. They came up with the "2 months salary" also as a way to justify buying bigger diamonds.
https://www.news.com.au/world/breaking-news/saudi-prince-tape-silence-khashoggi/news-story/5e12dd3ac82e50215fb5846bad188f46
Saudi prince 'tape': 'Silence Khashoggi'
A Turkish website says the CIA has signalled the existence of a tape of Saudi prince Mohammed bin Salman saying 'silence Jamal Kashoggi'.
Dominic Evans
ReutersNovember 22, 20189:48pm (Australia news)