ANKARA — Gold was the most profitable investment in March, according to the Turkish Statistics Institute on Wednesday.March's gold profit rates based on the Domestic Producer Price Index (D-PPI) were 2.20 percent while it was 1.81 percent, based on the Consumer Price Index (CPI).Gold's profit rate was 10.92 percent based on D-PPI, making it the most highly profitable financial tool during the first quarter (Q1) in 2014. Based on CPI, Gold's profit rates was 13.01 in the same period.Based on D-PPI, investors, who used the Dollar currency, lost 0.50 percent in their money's value and 0.32 percent in interest rate during March.