Diamond exports from India, which polishes about 90% of the world’s rough diamonds, will collapse by as much as a quarter this year as the pandemic crushes demand and breaks supply chains.

Overseas sales of cut and polished diamonds may slump 20% to 25% in the year ending March from $18.66 billion last year, according to Colin Shah, chairman of the Gem & Jewellery Export Promotion Council. That will push exports to the lowest in data going back to the 2009 fiscal year on the association’s website.