This is what I've been told for many years. In the 70's Colombia was growing at least four different cultivars... "Mango Biche", "Punto Rojo", and two others I don't remember now, but none of these were intially called "Golden". Till this day, Mango Biche and Punto Rojo remain our most known cultivars. Punto Rojo is charactized by red or purple pistils, it's said to be from a different region in Colombia than the others. It has very thin leaves and extremely fluffy buds.
During the 70's (and still today) these four cultivars were grown in several parts of the country, but the crops that were sent to the US were mostly grown in a place in Colombia called "Santa Marta", which is a city facing the caribean sea near "Sierra Nevada" and contains several micro-climates. From this place another cultivar eventually emerged and was called here "Santa Marta Gold", but it appears it was just those 4 initial strains but with stems being stripped which caused the golden effect.
So, it's said around here that the term Colombian/Santa Marta Gold was given by foreigners to refer to Colombian cannabis that came from Santa Marta, but that Golden variety was actually one of those 4 cultivars... all them grouped under the same name by north Americans.
Now a days, some Colombian growers have what they claim is Santa Marta Golden, which many others think is a mixture of 4 strains naturally breeding in Santa Marta throughout these 50 years.