The question of whether sterling silver is softer than gold is common because both metals, in their pure form, are quite soft. The simple answer is that the gold alloys typically used in jewelry are significantly harder than sterling silver. Jewelry is almost never made from pure gold or pure silver, as these metals lack the structural integrity needed for daily wear. To address this, both metals are combined with other elements to create alloys that are durable and retain their beauty. This process of alloying is the reason for the difference in hardness between these two common jewelry materials.
The Role of Alloying in Jewelry Metals
The physical properties of gold and silver are fundamentally altered when they are mixed with other metals, a process known as alloying. Pure silver is very malleable and prone to damage, so it is alloyed to produce sterling silver, the industry standard. Sterling silver maintains a precise composition, consisting of 92.5% pure silver and 7.5% of other metals, most commonly copper. The copper atoms disrupt the neat, uniform structure of the silver atoms, creating internal stress that makes the resulting alloy much stronger than the fine silver alone.
Gold alloys, on the other hand, are measured using the karat system, which indicates the proportion of pure gold out of 24 parts. Pure gold is 24-karat, but it is rarely used in fine jewelry because it scratches and deforms easily. To increase durability, gold is combined with metals like copper, silver, zinc, or nickel. A lower karat number signifies a higher percentage of these hardening base metals, meaning 14-karat gold, which is 58.5% pure gold, contains a larger proportion of strengthening alloys than 18-karat gold, which is 75% pure gold.
Measuring the Relative Hardness of Silver and Gold
Metallurgists use specific scales, such as the Vickers hardness test, to quantitatively compare the resistance of different materials to indentation. On this scale, sterling silver typically registers a hardness value ranging from 60 to 100 HV, depending on the specific manufacturing process. This measurement shows that while the copper alloy strengthens the silver, it remains relatively soft compared to many gold alloys.
The common gold alloys show a much higher resistance to deformation. For instance, 14-karat gold registers a Vickers hardness value between 150 and 200 HV, which is substantially harder than sterling silver. Even 18-karat gold, which has a higher pure gold content and is therefore softer than 14-karat, still typically measures between 125 and 180 HV, placing it at a greater hardness than sterling silver.
Practical Implications for Jewelry Care and Longevity
The measurable difference in hardness directly influences how each metal withstands daily use and wear. Because sterling silver is generally softer than common gold alloys, it is more susceptible to scratching and denting when exposed to abrasive surfaces or impact. A sterling silver ring worn daily, for example, is likely to show signs of surface wear and require more frequent polishing to maintain its original luster.
The higher durability of 14-karat gold means it can be used for thinner, more delicate designs, such as prongs holding gemstones, without compromising structural integrity. Sterling silver is prone to tarnishing, a chemical reaction with sulfur in the air that causes discoloration, necessitating regular cleaning and polishing. Gold, even in its alloyed form, resists this type of chemical degradation, contributing to its longevity and lower maintenance requirements.