I hope others point this out, the cost of gold ( nor any other
   commodity ) is so simplisticly tied to the price of production.
   Without doing any googling for specific numbers:
   - the price rise of gold in the past decade.
   - is the production costs of mining gold getting more or less
   expensive?
   alright ... here are some numbers:
   total cost of production example: 670 per ounce
   need I quote the current price of gold per ounce?  Note, that AISC is
   just one regions cost - others are plus or minus a hundred or so.
   [1]http://www.trefis.com/stock/abx/articles/206888/an-analysis-of-barri
   ck-golds-two-most-important-mines/2013-09-24
   ​and in pretty pictures:
   [2]http://www.visualcapitalist.com/what-is-the-cost-of-mining-gold
   ​
   ​It is the 'other factors' of commodities which drive prices.  Biggest
   is the cartel which controls that particular commodity - think diamonds
   for easy picture, Read about Libor, ISD etc:
   [3]http://www.rollingstone.com/politics/news/everything-is-rigged-the-b
   iggest-financial-scandal-yet-20130425
   ​-daniel

References

   1. http://www.trefis.com/stock/abx/articles/206888/an-analysis-of-barrick-golds-two-most-important-mines/2013-09-24
   2. http://www.visualcapitalist.com/what-is-the-cost-of-mining-gold
   3. http://www.rollingstone.com/politics/news/everything-is-rigged-the-biggest-financial-scandal-yet-20130425