Some old coins with a hole in them are valuable. A hole in a coin can also cause the value of the coin to decrease.
A number of people collect coin necklace pendants. The value of these pendants vary based on the coin used, its condition, the metal's value, the age and rarity of the piece, and the pendant maker. The more valuable coin pendants are the ones without holes in them. Modern coin pendant makers create a case for the coin, which features a loop to attach to the necklace. These are more valuable because the damage to the coin is minimal.