Why Pure Gold Doesn't Tarnish

Gold is one of the most renowned and widely used metals worldwide, valued for its beauty, rarity, and unique chemical properties that distinguish it from other metals. You might wonder why gold doesn't rust like iron or copper. What scientific factors allow this metal to maintain its shine over the years without corroding or changing its form? In this blog, we will explore gold's chemical properties, discuss why it is among the most stable metals, and explain how these qualities have made it a preferred choice for jewellery and investment throughout history.

Pure gold doesn't tarnish because it is a noble metal, meaning it is chemically inert and doesn't easily react with elements like oxygen or moisture found in air and water. This stability makes pure gold resistant to rust and corrosion. However, most gold jewellery contains alloys of other, less resistant metals, and it's these base metals that can tarnish over time, not the gold itself. 

The higher the gold’s karat (more gold and fewer reactive alloy metals), the greater the gold content. Therefore, the lower the gold content (18k and below), the more likely it is to tarnish over time. In general, 24k and 22k gold do not tarnish due to the amount of gold they contain.

Why Does Gold Not Tarnish?

Gold’s resistance to rust is due to its chemical makeup. As a noble metal (classified alongside platinum and silver), gold is highly inert. It doesn’t easily bond with oxygen or other reactive elements, which is why it doesn’t corrode or tarnish over time. Gold is one of the least reactive metals on the periodic table, which accounts for its stability.

Chemistry of Gold

Due to its stable electron configuration, gold forms fewer bonds with other elements, such as oxygen. Gold's high stability prevents it from oxidising, whereas copper and iron, with their more reactive electron configurations, are more susceptible to oxidation.

Causes of Gold Jewellery Losing Lustre

Pure gold does not generally tarnish. However, several factors, such as environmental conditions, can cause gold to lose its lustre. Furthermore, regular exposure to high humidity levels may induce a chemical reaction on the surface of the jewellery, causing it to lose brightness over time.

Chemical Exposure

For instance, gold’s exposure to strong chemicals, such as perfume, hairspray, lotions, and other cleaning supplies like chlorine, bleach, and laundry detergents, contains chemicals that could adversely affect the surface of gold jewellery.

How to Prevent Gold from Losing Lustre

Cleaning your gold jewellery regularly helps prevent oxidation and maintains its shine. It is advisable to clean your gold jewellery using a commercial jewellery cleaner specifically designed for gold. These products are commonly available at jewellery stores or online. Additionally, ensure that you follow the instructions on the label carefully, considering the type and quality of your gold. Before applying it to the entire piece, test the cleaner on a small, hidden area first to ensure it doesn’t cause any damage or unwanted reactions.