Does Platinum Have Carats? How Purity Is Measured

Platinum is a lustrous and durable precious metal, valuable in both industrial applications and fine jewelry. Understanding how its purity is measured is fundamental for consumers and investors. While “carat” is often associated with precious metal purity, its application varies significantly depending on the specific metal. This distinction is important for accurately assessing the quality and worth of platinum items.

Understanding “Carat” in Precious Metal Purity

The term “carat” carries different meanings for precious metals versus gemstones, which can lead to confusion. For gold, “carat” (often spelled “karat” in the United States) is a unit of purity, not weight. It indicates the proportion of pure gold within an alloy, measured on a scale of 24 parts.

For instance, 24-karat gold signifies pure gold (24 parts out of 24). An 18-karat gold item contains 18 parts gold and 6 parts other metals, making it 75% pure. 14-karat gold is 14 parts gold, or 58.3% pure.

In contrast, when discussing gemstones like diamonds, “carat” refers to a unit of weight. One metric carat is precisely equal to 200 milligrams (0.2 grams). This quantifies the gemstone’s mass, influencing its size and value. The “carat” system for purity is specifically designed for gold alloys due to gold’s relative softness in its pure form, which necessitates alloying with other metals for durability in jewelry. It is important to note that “carat” is not used for platinum’s purity or weight.

How Platinum Purity is Expressed

Platinum’s purity is expressed using percentages or parts per thousand, known as millesimal fineness. This system indicates the proportion of pure platinum in an item. Common markings for platinum jewelry include “950 Plat” or “950 Pt,” signifying 95% pure platinum. Other common purity levels include “900 Plat” or “900 Pt” for 90% pure platinum, and “850 Plat” or “850 Pt” for 85% pure platinum.

These markings are typically stamped onto the platinum item, often alongside “Pt” or “Plat,” to guarantee its purity. The U.S. Federal Trade Commission (FTC) guidelines state that for an item to be called “platinum,” it must contain at least 500 parts per thousand of pure platinum. Most platinum jewelry sold in the U.S. contains at least 90% pure platinum, with 95% purity being a widely accepted standard for high-quality pieces. Hallmarks also include symbols indicating the maker or the assay office where the metal was tested.

Valuation and Investment Implications

Market prices for platinum are quoted per troy ounce of pure platinum, similar to gold. The percentage purity of a physical platinum item directly impacts its intrinsic metal value when bought, sold, or appraised. An item marked “950 Pt” contains more pure platinum than a “900 Pt” item of the same weight, directly affecting its market worth.

Investors and consumers must recognize these differing measurement standards to ensure fair pricing. When purchasing platinum, verifying the fineness mark ensures the item’s metal content aligns with its price. This knowledge also helps financial professionals assess precious metal assets for inventory, collateral, or estate appraisals. Platinum’s price is influenced by industrial demand, supply, and global economic trends, making purity a fundamental factor in its value and investment potential.