Counterfeit Coin

You are given 12 nearly identical coins. 11 of the coins are exactly the same with 1 coin being a fake. The fake coin is slightly lighter or heavier than the rest of the coins, but you aren't sure which. You don't have any way to weigh the coins except for a balance. The balance will not show the exact weights of the objects placed on either side. It can show if the two sides have equal weight or can show if one side is heavier/lighter than the other. Unfortunately, you can only use the balance three times before it breaks. Additionally, you have a marker that you can use to write on the coins. Writing on the coins will not change their weight.

How can you correctly identify which coin is the counterfeit?

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