Platinum and silver are both popular white metals used in jewelry, often appearing similar. However, these two materials differ greatly in their physical properties, chemical behavior, and overall value. Understanding the distinction is important for determining the true worth of an item and ensuring correct long-term care. Simple methods focusing on official markings, density, and chemical stability can help identify which metal you possess.
Reading the Official Stamping
The most direct and non-destructive way to distinguish between the two metals is by locating and inspecting the hallmark. Precious metal items sold commercially are legally required in many regions to carry markings that indicate their exact composition. Platinum jewelry typically uses a high purity standard, most commonly marked as “950 Plat,” “PT950,” or simply “PLAT.” This signifies that the piece is 95% pure platinum.
Silver items are usually marked with “925,” “Sterling,” or “Sterling Silver.” The “925” stamp indicates a composition of 92.5% silver, which is the international standard for sterling silver. A piece without a visible purity mark is less likely to be platinum.
Differences in Weight and Durability
Once the markings have been examined, the next difference between the two is their relative mass, which relates directly to their density. Platinum is an extremely dense metal, possessing a density of approximately 21.45 grams per cubic centimeter. In contrast, silver is much lighter, with a density of about 10.49 grams per cubic centimeter.
This scientific difference means a platinum item will feel substantially heavier than a silver item of the exact same size and design. This physical property is a reliable indicator, as platinum is roughly twice as dense as silver.
The metals also differ significantly in their long-term durability and resistance to physical wear. Sterling silver is a relatively soft material, ranking about 3.0 on the Mohs hardness scale. This softness means that silver jewelry easily picks up scratches, bends, and wears down over time, often requiring frequent maintenance to restore its shape.
Platinum is much tougher and more resilient, ranking between 4.0 and 5.0 on the Mohs scale. When platinum is scratched, the metal is not actually lost but rather displaced across the surface, creating a unique texture known as a patina. This characteristic ensures that platinum settings maintain their structure and hold gemstones more securely over many years of daily use.
How Each Metal Reacts Over Time
The most telling distinction lies in the chemical reactivity of the two metals when exposed to the environment. Silver is highly susceptible to tarnishing, a process of surface chemical corrosion. The dark film that develops on silver forms when the metal reacts with airborne sulfur compounds.
These sulfur compounds are present in trace amounts in the atmosphere. The resulting black layer requires regular polishing to remove, making silver a material that demands consistent, hands-on maintenance to retain its bright, reflective finish. Every time silver is polished, a small amount of metal is removed with the tarnish layer.
Platinum, conversely, is classified as a noble metal, meaning it is exceptionally resistant to chemical attack, oxidation, and corrosion. It does not react with oxygen or sulfur compounds in the air, ensuring that a platinum piece will never develop a tarnish layer. This inert nature is why platinum maintains its bright, natural white color without the need for plating or frequent chemical cleaning methods.
The maintenance required for platinum involves simple washing with mild soap and water to remove surface dirt and oils. The persistent presence of any black or dark discoloration that can be wiped away with a polishing cloth is a strong long-term confirmation that a piece is silver and not platinum.