An auction can give you a good idea at how the market is moving and what price gold coins are trading at in the private sector of the market.
Collectors will pay higher prices if the year for instance is the one that they need to finish a collection that they have been putting together for years and also if the gold coin has a history around the time it was first minted.
So the value of gold coins is dependent on a number of factors.
1. A coin might be rare .2. The coin might have an interesting history.
3. A collector might be willing to pay more if the coin is needed to finish a collection, say a certain year or the weight class.
4. The condition of the coin, scratched, worn or even distorted.
Ultimately gold coins are segregated into two camps. Camp A are those that are standard bullion coins which sell for pretty much the base value of gold and there is camp B where the collectibles move in. If you're an investor , you can move between both camps but camp B is a lot trickier as you need to know a lot about what you are buying. Camp A requires you to know when to buy and sell your gold coins which is tricky in a different way.
Below is a realtime auction taking place.

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