18K GF Necklace with Onyx This is a used item. It shows considerable signs of wear. It looks old. There are areas where the color has faded. Gold plating and gold-filled refer to the following processing methods: Gold plating (GP: Gold Plated)… Creating a thin film of gold using electricity Gold-filled (GF: Gold Filled)… Applying a thin sheet of gold with heat Gold plating and gold-filled have three advantages: They can make products look beautiful and give them a luxurious feel. They can prevent rust and discoloration of products. Since the products are not pure gold, they can be made inexpensively and with high strength. Gold has advantages such as "not rusting, not discoloring, and having a luxurious feel," but it has the disadvantage of making the manufacturing cost of products very high. This is where gold plating and gold-filled come into play. Gold plating and gold-filled can be applied to strong products such as iron, and they are methods that can easily give a luxurious feel. Also, since the amount of gold used is small, the material cost of the product can be reduced compared to using gold throughout.