
Colombia's tinted gold passes for precious stones
• phys.org,by Raul Arboleda and Carlos Osorio"It does not involve painting the gold or covering it with some material that disguises the traditional white, yellow or pink of the precious metal," said Maria Eugenia Carmona, the principal researcher on the project.
"It involves subjecting it to an elaborate thermochemical process of eight to 10 hours, after which not only does its color become red, blue or green, among others, but also its market price increases significantly," she said.
Colombia extracted 56 tons of gold from its mines in 2011, representing a 4 pcercent increase over the previous year. Colombia's gold exports were valued at $2.8 billion in 2011, a 31.4 percent increase, according to official figures.
Colombia, Peru and Mexico are Latin America's biggest gold producers.