A very good question indeed.

I asked the same question to people that are well-informed about the Crystallex - Venezuela deals and for an answer I got three questions. One of these was: How do you think that the Venezuelan Central Bank has been able to buy over $1.0 billion of gold mined from the kilometer 88 area (as Crystallex's Las Cristinas and Gold Reserve's Las Brisas gold mine area is commonly known in Venezuela) over the last couple of years from the gold mining enterprise led by the Venezuelan army and the Colombian guerrila that control it for their own benefit as well as  Maduro's government? By miners hitting the mother load by sheer luck?

Gold Reserve's settlement with Venezuela includes a conditio sine qua non that the mining data for its Las Brisas mine will only be turned over to Venezuela after its settlement agreement with Venezuela is paid in full.

The link below will take you to a Miami Herald article that explains how the gold is extrated trade in Venezuela's wild south. It only fails to mention that the Central Bank pays for the gold with Bolivar bills it gets printed at will.

https://www.miamiherald.com/news/nation-world/world/americas/venezuela/article232672327.html