The allure of gold has been with mankind for centuries. However, all gold is not the same, and within gold processing different types exist, including pure gold, gold plating and gold alloys. 18-carat gold is a solid gold alloy, whereas gold plating, even if 18-carat, is just a covering over a different type of metal.
In terms of purity, 18-carat gold is 75 per cent gold, as opposed to 24-carat, which is 100 per cent pure gold. Each carat grade contains a different percentage of gold mixed with other metals, depending on the gold being produced. Since gold is a soft metal and can be damaged or worn down easily, gold blended with stronger metals is preferred for jewellery and other pieces that are used often.
Each type of gold is blended with different metals, depending on the colour desired. According to Enchanted Learning's gold page, an 18-carat yellow gold piece is 75 per cent gold with 25 per cent of it consisting of a 50/50 blend of silver and copper. An 18-carat white gold piece is a 25 per cent blend of equal amounts of nickel, zinc, copper, tin and manganese. Other gold colours produced by different compositions include: pink, green, blue and grey gold (see Reference 1).
Gold plating refers to a layer of gold applied over a base metal. The three types are gold plate, gold fill and gold leaf. According to E-Gold Prospecting, all gold plating must be at least 10 carats or higher, and the application processes differ: Gold plating is accomplished through a process called electroplating; gold filled means the overlay is bonded through a heat and pressure process and gold leaf is a plating applied by hand (see Reference 3).
Plating Pros and Cons
Each method of plating produces a gold product that wears differently. While gold leaf is used mostly for decorative purposes, such as architectural motifs, filled and plated gold is used for jewellery and items that are handled and used. According to Gem-Fashion, gold-plated items wear quickly due to polishing and exposure to body salt, while gold-filled pieces have a longer lifespan, reflected in their higher price (see Reference 2).