In fact, gold prices have never been stable. Recently, the price has been slowly but surely declining:

In the last half-year gold lost almost 15% of its value, from $1,366 in this July down to $1,183 per troy ounce today. Some are claiming that gold might eventually drop to 850-650 dollars, though I don't really believe it can fall significantly below the $1,000 mark due to powerful support from the gold bugs around that level...
In any case, to think of gold prices as something rock solid has more to do with wishful thinking than harsh reality
I would not regard a 2 month period a reasonable investment timeframe as you show in your chart above. I also still believe the fundamentals for gold are very strong in the mid term when you consider world debt, increase in money supply and the turmoil across the globe that feeds gold price.