One of the several odd things I've done in my life was work as a precious metals inspector, and I can tell you that the only thing you want to invest in if you are looking at gold are ingots that are refinery stamped, serialized, and certified for weight and purity ( at least .9999% pure) almost everything offered on TV is crap.
Without naming names, (NDA) I can tell you that the unsold product ends up at a refinery, and once they sparge* and salt off* the impurities and base metals, there is nothing left.
( *Different base metals combine with different things at different temperatures - Sparging introduces oxygen into a pot of molten metal and it combines with waste metals such as lead and becomes lightweight floating slag on the top of the pot that can be skimmed off. Salting off involves doing a similar thing but with chlorine gas, and is usually done to remove good metals (copper, silver, etc.) from gold by producing Copper Chloride, Silver Chloride, etc. which also floats to the top of the pot to be removed. There are other ingredients involved but again, NDA and all that.)