The group said steady US demand supported the market but overall demand was sluggish, with Britain’s decision to leave the EU, the US election and continued weakness in China’s luxury sector fueling uncertainty.
The price of 3-carat diamonds decline 2.4%, while 0.30-carat diamonds dropped 1.6% and 0.50-carat diamonds dipped 0.4%.
The price of 1-carat diamonds fell 0.7% in the second quarter of the year, reversing some of the gains made in the first three months of the year. Despite this, the price of 1-carat diamonds grew 0.7% in the first half of 2016 when compared with the same period last year.
Rapaport said the diamond markets slowed in the second quarter of the year, with selective buyers pushing for deeper discounts. Polished inventory continued to rise and prices came under pressure, while rough trading remained resilient.
Martin Rapaport, chairman, said: “The diamond industry is being challenged by low profitability, tight liquidity and sluggish demand. It is vital that rough diamond producers maintain price levels that ensure profitability and liquidity in the manufacturing sector during these uncertain times.”