When the first explorers traveled the world and found gold in different places, they realized that not all gold is the same color. Some of the earliest gold findings were a metal known as Electrum, a mixture of gold and silver with a slightly pale greenish color. Other findings showed gold with a reddish tint. When two metals dissolve each other (as is the case with alloys), the color is often a mixture of the two.
For example, copper dissolved in gold changes the color from yellow gold to red gold. Silver dissolved in gold creates a green-gold color. White gold contains palladium and silver. The color of gold jewelry can be attributed to the addition of different amounts of various metals (such as copper, silver, zinc, etc.).
Some of these color changes can be explained by changes in energy levels relative to the Fermi level. The graph shows the percentage of the mixture between metals that will result in different shades of gold. While the most common colors in which gold is found are yellow, white, pink, and green, you can break down gold into at least eight shades. At first glance, it is difficult for an inexperienced eye to distinguish between white gold and sterling silver.
Both are silver in color, but the two metals are very different beyond their initial appearance.