Golden coins are fine. Magic should be foremost practical. The best coin to use is one minted in your birth year. You can also scratch your initials into the coin to further personalize it to you.
In the United States we have a ton of folk magic relating to silver coins. People typically use a Liberty Dime, and employ such coins for a variety of reasons - as a warning when a curse is thrown, psychic defense, gambling luck, and money-drawing. These coins are no longer minted any more, but can be found online and through old coin dealers relatively inexpensively. These Liberty Dimes used to have a goodly amount of Silver in them, which contributed greatly to their magical properties. Nowadays our new dimes have no silver in them, but people still use them all the same. Magic evolves by what materials people have readilty available to them.