Diamonds may be a girl's best friend, but that camaraderie hasn't been enough to avert a slowdown in sales of the pricey stones.
According to a new report by the consulting firm Bain & Co., retail sales of diamond jewelry are expected to rise a maximum 2 percent in 2015, compared to last year's 4 percent increase.
There are several factors contributing to the slowdown. Among them: Softness in the overall luxury goods market, changing consumer attitudes and a pullback in demand from the China market.
"The second half of  and the first half of 2015 have been characterized by a degree of uncertainty in the diamond industry," the report said. "The primary source of this uncertainty is China's slowing GDP growth."
According to Bain, the largest Chinese diamond jewelry retailers reported a 9 percent decline in sales during the first nine months of the year, as compared to the same time period in 2014. In addition to slowed GDP growth, the Chinese stock market crash in June caused a decline in consumer confidence, which also took a toll on the diamond market, Bain said.
Growth in the United States has helped offset weakness in China, though Bain noted that it, too, faces long-term challenges. For one, "luxury items are forfeiting their aspirational and status appeal in developed markets," as it's become passé for Americans to showcase their wealth. For another, little is known about the tastes of the next generation of consumers.
To that point, The Knot's 2015 proposal and wedding jewelry survey found that 8 percent of brides received an engagement ring with a nonprecious stone; that's up from 6 percent in 2013.
Diamonds, however, remain the most popular stone among U.S. couples, at a whopping 84 percent.
According to The Knot, the amount grooms are spending on the engagement ring is at an all-time high of $5,978 on average, compared to $5,403 in 2013.