The largest of the smaller producers, Petra Diamonds has been hit particularly hard, with the shares down 38% in the past year. Workers went on strike in South Africa earlier in September and the company missed production goals.
Gem Diamonds sank 34% in the past year. The company closed and put up for sale its new mine in Botswana following a slump in small gem prices.
Lucara also produced less than expected and took more than a year to offload the biggest diamond found in more than a century - eventually at a lower price than anticipated. The stock slumped 38% in the past year.
Firestone, Mountain Province
Newer producers, Firestone Diamonds and Mountain Province Diamonds, also stumbled. They have ramped up output, but stones sold for less than expected.
The diamond industry is dominated by two giants, De Beers and Alrosa, and several companies that are a fraction of the size.