Global diamond jewelry sales grew 4% to $ 85.9 billion in 2018, despite a weaker second half, according to market research, says the Russian miner Alrosa.

The growth was slower than the 5% increase Alrosa reported last year. North American sales grew 4% in 2018, while the region accounted for more than half of total sales, the company said.

In the first half of the year, high demand from local consumers and tourists in key markets led to a 6% increase in global sales. However, demand declined in the second half of the year as the US dollar strengthened against other currencies, with total global revenue growth of just 2%, Alrosa noted. Sales in Asia, including Southeast Asia and India, increased by 5% during the year.