The question of whether gold or silver is stronger is common, yet the answer is not simple, as “strength” refers to several distinct material properties. Gold (Au) and silver (Ag) are both classified as noble metals, meaning they resist corrosion and oxidation in moist air. However, they possess different mechanical and chemical characteristics. The practical durability of these metals, especially in common uses like jewelry, depends heavily on whether mechanical resistance to force or chemical resistance to the environment is being measured.
Defining Physical Strength in Metals
In metallurgy, a metal’s strength is defined by its resistance to different types of mechanical stress. Hardness describes a material’s resistance to permanent localized deformation, such as scratching or indentation. While the Mohs scale is a common reference, more precise industrial scales like Vickers or Brinell are used for engineering. Tensile strength measures the maximum stress a metal can withstand before it breaks when being pulled apart. This property is particularly relevant for thin chains or prongs holding gemstones. Separately, ductility and malleability describe a metal’s ability to be shaped without fracturing. Ductility is the capacity to be drawn into a thin wire, while malleability is the capacity to be hammered or rolled into a thin sheet.
Mechanical Comparison of Pure Gold and Pure Silver
In their purest forms (24-karat gold and 99.9% fine silver), both metals are notably soft and highly workable. Both pure gold and pure silver score around 2.5 to 3.0 on the Mohs hardness scale, making them easily scratched and dented. Pure silver is technically slightly harder than pure gold, with a Vickers hardness number of approximately 251 compared to gold’s 216.
Silver also exhibits a marginally higher tensile strength, measuring about 140 megapascals (MPa) versus gold’s approximate 120 MPa. Although silver is slightly more resistant to breaking when pulled, both pure metals are still too soft for high-wear items. Gold is significantly denser at 19.32 grams per cubic centimeter, making it nearly twice as heavy as silver, which has a density of 10.49 grams per cubic centimeter.
How Alloying Determines Practical Durability
Because pure gold and silver are too soft for practical use, their functional strength comes almost entirely from alloying—mixing them with other metals, most commonly copper. The addition of a non-precious metal disrupts the uniform arrangement of atoms in the pure metal. This makes it much more difficult for the atoms to slide past one another, thus increasing hardness and yield strength.
For gold, a lower karat rating means a higher percentage of alloying metals, resulting in greater mechanical strength. For instance, 14-karat gold is 58.3% gold, with 41.7% alloy, which is harder and more resistant to wear than 18-karat gold (75% gold). The Mohs hardness of 14-karat gold is around 3.0, while 10-karat gold, with the highest alloy content, can reach 3.5.
Silver is most often alloyed to create Sterling silver, which consists of 92.5% silver and 7.5% copper. This small copper addition increases its tensile strength significantly, sometimes to over 400 MPa, a figure higher than many gold alloys.
However, 14-karat gold is generally considered harder and more durable than Sterling silver in common jewelry materials. This is due to the much larger proportion of hardening alloy metals in the 14-karat gold mix. White gold alloys, often made with metals like nickel or palladium, are specifically engineered to maximize hardness and durability. Palladium-based white gold is highly resistant to scratching. Therefore, an optimized gold alloy like 14-karat is often the more mechanically durable material for everyday wear.
Chemical Stability and Resistance to Tarnishing
The comparison shifts dramatically when considering chemical strength, which measures a metal’s resistance to environmental degradation. Gold is one of the most chemically stable elements, a characteristic that defines its noble status. Pure gold does not react with oxygen, sulfur, or water, meaning it is completely resistant to tarnishing, corrosion, and rust.
Even gold alloys, such as 14-karat or 18-karat, maintain a high degree of chemical stability because the gold content protects the other metals. Any minor discoloration that occurs in gold alloys is usually a very slow, superficial oxidation of the non-gold metals, like copper. Silver, by contrast, is chemically reactive to sulfur compounds present in the air. This reaction forms silver sulfide, the black film known as tarnish. While tarnishing does not affect the metal’s structural integrity, it is a chemical weakness that necessitates regular cleaning and maintenance. For long-term resistance to environmental factors, gold is the stronger choice.