If you ever want to turn coins into gold or gold into coins, you can do that at any Auctioneer using the Gold Trading option. Below you will see an explanation for exactly how to do this.
Buying and Selling Gold From the Auction House
At the Auctioneer NPC in any major city, start dialogue and choose Gold Trade.
This is the window that automatically opens up. The three buttons at the top: Buy, Sell, and Password are fairly self-explanatory. The buy button lets you buy gold, the sell button lets you sell gold, and the password button allows you to set and change the account password.
The rest of the window can be divided into four basic sections: the Set Price window, the Available Funds window, the Price Listings, and the bottom area.
The Set Price Window
This area in the upper left of the window, is where you set your prices for buying and selling. Regardless of whether your buying or selling, the layout is the same. The price box is where you set the amount of money in coins. This is how much you want to spend for buying, and your price for selling. This needs to be in a value that is divisible by 100. The amount box is the amount of gold you want to buy or sell, and must be less than 100. Input the amount you wish to use for each. For buying prices, it will take the lowest price under whatever value you set first. For example, using the above image, if I placed the value of 1,600,000 in price, and 10 in amount, it would take the gold from the next lowest (1,599,900) first.
The value next to Total is the amount of money you will spend or make, again depending on whether your buying or selling. Fee is an additional cost that goes to the NPC, paid in coins for buying, and gold or silver for selling. This fee is 2% of the total for everything. Using the example above, the fee paid would be 319,980 coins. This is the same regardless of how much you actually spend.
The Available Funds Window
This is located just under the Set Price window, and lists how much gold and coins you have available for use. It is not how much of each you have in total, but just what can be used for gold trading. To use gold and coins here, you must first deposit them by clicking on the Deposit button. This brings up the following window:
Type in the amount of coins and gold you want to use for trading into the appropriate box, and hit done. You can put all your coins or gold in if you wish by hitting max, and the done. This will make the coins and gold usable in your trading account. However, you can't using this money in other places in the game unless you withdraw it from the account. This is done in the exact same way as depositing, but click on the Withdraw button instead. This will make the funds usable in other places, but remove it from the gold trading account.
The Buy and Sell Window
Found to the right of the screen, this lists all the prices for currently available gold. When you sell gold, the prices will be listed in the upper window in yellow. For buying gold, the prices you wish to buy at will be found at the bottom in green.
This means that should a person buying gold list a lower price than what is found in the upper, yellow section, it will be placed in the lower green section.
The Bottom of the Window
This area contains other sources of information. The Players Funds area on the right shows how much is available outside the gold trading account. On the left, the refresh button simply updates all windows to reflect changes made by all players using the gold trading. Clicking on Listings will bring up a new window:
This shows all current transactions, similar to the Auction House. The buy and sell prices listed here go into more depth than the opening window, and show a wider listing. The left section of this window shows transactions currently in progress, as well as those that have already been completed in the past. If you wish to buy gold for a lower price than is listed in the yellow sell window, then it will show up in this area, as well as the green buy window.