Such flasks were used to hold lime, a substance chewed with coca leaves to release their active stimulant. This example was cast by the lost-wax method using tumbaga, an alloy of copper and less than 60% gold. The lower legs were added in a second casting. Its surface was treated by depletion gilding and then burnished. Depletion gilding consists of the removal (or depletion) of copper, and sometimes silver, from the surface of a copper-coloured tumbaga object, giving the finishing appearance of a much higher purity gold.For many Ameridian cultures the practice of enriching the surface appearance of gold alloys used for body ornament and ritual regalia was motivated by the symbolic significance of gold. Their perceptions and values differ fundamentally from much of Western thought. Many of the surviving gold artefacts reveal great sophistication in technology and design. The reflective properties of the surface of the golden object was probably more important than the purity of the gold itself. Indigenous people in present-day Colombia believe that there is a reciprocal relationship between the gold and the sun, in which energy is exchanged.