At the center of the pain are the middlemen who cut, polish and trade the world’s diamonds. Their profits evaporated as polished stones lost value, banks tightened financing, and top producer De Beers held firm with prices it demands for the rough diamonds it digs up.

This year, the crisis has spread to engulf the world’s diamond miners as well. Even De Beers, which dictates prices to its select group of clients, has been getting squeezed as struggling customers refuse to buy. Last week, the iconic miner finally capitulated, lowering prices across the board, which helped to increase sales at its latest offering in Botswana.

Still, the results were relatively weak. The $390 million in rough diamond sales this month is the lowest for a November round since at least 2016. The price cut is unlikely to be enough to make a difference for De Beers customers, who have been struggling to make profits for more than 18 months.

Read: De Beers Diamond Buyers Return After Biggest Price Cut in Years

Not all diamonds are getting cheaper. Sales of the type of luxury, branded jewelry sold by Tiffany & Co., Cartier or Bulgari have been resilient and grabbing market share in the $80 billion industry. However, they still only account for about 30% of the global total.

In the rest of the market, diamonds are treated more like a commodity, judged on the famous 4Cs: color, clarity, cut and carat weight. Without branding, there’s little to differentiate one ring or stone from another — other than price — and consumers can scope out the going rate on online stores like Blue Nile.

As a result, polished prices have been falling, as the thousands of companies that cut and polish the gems are squeezed by retailers who are in a great spot to negotiate. An index that tracks wholesale diamond prices is near the same level as 2002 and consistently declined since 2011.

“There are tons of players out there and they’re in competition with each other,” said Anish Aggarwal, a partner at specialist diamond advisory firm Gemdax. “This gives retailers huge buying power, which can be used to keep polished prices lower than they could be.”

At the same time, diamond demand has been steady or rising. In the U.S., which accounts for 50% for sales, demand grew 4.5% last year and Americans spent $36 billion on diamond jewelry. But with ample supplies of polished stones, prices have remained stubbornly low.

Read: De Beers Cuts Diamond Prices by About 5% as Crisis Deepens

Diamond traders have lots to worry about. There’s been an oversupply of rough diamonds in recent years, especially in smaller gems. Retailers are holding less inventory, forcing suppliers to keep more stock at a time that prices are falling. Banks have also been abandoning the sector, cutting off credit to an industry that has grown accustomed to cheap money.

De Beers has offered its buyers more flexibility around their purchases, but it hasn’t been enough and sales this year have slumped. Still, the drop in rough diamonds being sold by De Beers and Russian rival Alrosa PJSC may represent a silver lining for the industry if it helps to reduce inventory logjams.

The Anglo American Plc unit is also throwing more money into advertising. The company cut spending dramatically after its monopoly ended at the beginning of the century, but in recent years has turned the taps back on.

De Beers will spend $180 million this year, its largest marketing budget in a decade, CEO Bruce Cleaver said in Botswana last week.

Still, there’s only so much the company can do to offset the impact of weaker pricing, said Aggarwal.

“Over time, De Beers’s fate is tied to polished prices,” he said. “In the short term, they can push the midstream hard, but it can’t last forever if it’s out of line with polished prices.”