The number of hours of work it takes to afford a one-carat diamond has trended downward in recent years and has fallen by almost half since 2011. Engagements rings are the pulse of the diamond industry, and marriage trends are a long-term factor driving prices of the gem, according to an industry report from Bain & Company. The challenges facing the sector include changing views in Europe, Japan and the US — where diamonds are being seen as less of a status symbol. It's hard to know what the next wave of consumers will make of them, according to the report.