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.