The common perception that the rectangular bits of gold ("bars") are the most cost-effective, and perhaps the only available, form of gold bullion. There are also perceptions that the round bits of gold ("coins") are not really bullion, that "coins" are in limited supply, expensive, and are only traded as collectors' items: These are also incorrect.
Gold coins are transferrable: they come in smaller values and are therefore easier to buy and sell. Coins also can have additional numismatic value beyond the spot price of their constituent gold or other precious metal. You can also explore the internet to get high-value coins online.
This is not just true for collectors' coins but investment-grade coins as well. Coins are also not as subject to the kinds of sudden movements of gold spot prices. As dips occur in the price of gold, investment-grade coins show resilience as they tend to glide over such valleys.
Not to be confused with "collectors' coins," investment-grade coins are purchased primarily as an investment. They are of the highest grades and rarity. Though they also have numismatic value their value is greatly determined by the value of their underlying metal.
The numismatic value tends to absorb short-term movements in metals, while the content of the coin influences its long-term value. The best gold coins for investment are government-minted bullion coins with low premiums and high liquidity.