We can thank (or blame) the diamond industry for inventing the idea that a groom should spend two month’s worth of salary on an engagement ring for his beloved, but an arms race of bling between celebrity brides is threatening to blow even that hefty budget guideline out of the water. The latest salvo comes from Kim Kardashian, whose ring, with its estimated value of $2 million, could easily take an average working man an entire lifetime to to afford.