After shocking the market with a decision to start selling jewellery containing synthetic diamonds, Anglo American’s De Beers is planning to let buyers refuse some lower-quality stones.

The unusual move (the world’s No.1 diamond miner is famous for requiring buyers to take what’s offered) says lots about the state of the low-end diamond market. The last time De Beers did something similar, in fact, was two years ago, when India’s move to ban high-value currency notes pushed down demand.

The diamond giant’s new strategy for small stones, paired with its looming entry into the lab-grown stones market, have many in the industry worrying about prices.

A 1-carat synthetic sells for roughly $4,000, about half the price of a natural diamond. De Beers new lab gems, to hit the market this month, will sell for around $800 a carat.

Cheaper diamonds, which are often small and low quality, are selling for a lot less now than five years ago. And when it comes to synthetic stones, De Beers’ entry in the market will create a big price gap between mined and lab diamonds, pressuring rivals that specialize in synthesized stones at the same time.

A 1-carat man-made diamond sells for about $4,000 and a similar natural diamond fetches roughly $8,000. De Beers new lab diamonds will sell for about $800 a carat. That’s a fifth of the price of existing man-made stones and one-tenth of the cost of buying a similar natural gem.

No wonder competitors are worried. The lab-grown industry has filed a complaint with the U.S. Federal Trade Commission, accusing De Beers of price dumping and predatory pricing.

They did so even though the government body recently amended its jewellery guides...

Read more from our friends at Mining.com