Platinum Identification
How to identify and value inherited platinum jewelry
Platinum looks a lot like white gold, and the two are frequently confused in inherited estates. But they are not the same metal, and the differences matter for value — especially in the Edwardian and Art Deco pieces where platinum was the premium metal of choice. This guide covers the marks that identify platinum, the physical differences that distinguish it from white gold, and why signed platinum estate jewelry commands strong prices in today's market.
Platinum versus white gold at a glance
Platinum and white gold share a similar cool silver-white appearance, but they differ in several ways. Platinum is significantly denser than gold — a platinum piece weighs noticeably more than a same-size white gold piece. Platinum's color is naturally cool and grayish; rhodium-plated white gold is often even whiter, sometimes with a subtle blue tone. Platinum develops a soft patina over time that can be polished back or left for character; white gold's rhodium plating wears off, revealing the slightly yellower underlying gold. The easiest check, though, is always the mark.
Common platinum marks
Modern American platinum is typically marked PT950 or 950, indicating 95% pure platinum with 5% alloy metals (typically ruthenium, iridium, or cobalt). Older pieces may carry PT900 or 900, indicating 90% pure platinum — a common alloy through the early 20th century. Pieces marked Plat or Platinum without a percentage are usually high-purity platinum, though the exact alloy may not be specified. Irid Plat or 10% Irid Plat indicates a platinum alloy with 10% iridium added for hardness — a common formula for Edwardian and Art Deco jewelry. All of these marks indicate genuine platinum, though the percentages affect both melt value and the working properties of the metal.
Platinum purity standards
The US standard is 95% platinum (PT950) for jewelry labeled simply as "platinum." Pieces with lower platinum content must specify the percentage or name the alloy clearly. Older American jewelry, particularly from the 1900–1940 era, was often 90% platinum with 10% iridium — an alloy valued for its slightly harder working properties. European and Asian platinum may use different standards, with some markets accepting 85% or higher as platinum. Always look for both the symbol and the percentage when present.
Why platinum was dominant in Edwardian and Art Deco jewelry
From roughly 1900 until 1940, platinum was the preferred metal for fine jewelry in the United States and much of Europe. Platinum's strength allowed jewelers to create the delicate filigree, millegrain, and openwork settings that define Edwardian and Art Deco jewelry — fine details that gold could not hold. Platinum's cool color let diamonds and pearls appear at their brightest. Platinum also held prongs tightly enough to secure stones with nearly invisible settings, a hallmark of the era's best work. Signed platinum pieces from this period are actively collected.
The end of the platinum era
Platinum's dominance in American jewelry ended during World War II, when platinum was designated a strategic metal and rationed for industrial use. White gold became the substitute. After the war, platinum returned to jewelry but never regained its pre-war market share; 14K white gold became the default for diamond rings and bridal jewelry. This history explains why most pre-1940 fine jewelry is platinum and most post-1945 white-metal jewelry is white gold, with newer platinum pieces typically representing higher-end recent production.
Melt value and market considerations
Platinum's density means a platinum piece has more metal by weight than a same-size gold piece, which affects melt value. Platinum and gold trade at similar per-gram prices most years, with fluctuations driven by industrial demand. At any given moment, platinum may be slightly more or less valuable per gram than gold — the long-term averages are similar. For finished jewelry, the metal is only one part of the equation. Important signed platinum Art Deco and Edwardian pieces routinely sell for many multiples of melt value because their design, workmanship, and provenance are what buyers are paying for.
Signed platinum estate jewelry
The strongest market for inherited platinum is in signed pieces by important 20th-century makers. Signed Art Deco platinum diamond rings, platinum filigree bracelets, and Edwardian platinum brooches can sell for tens of thousands of dollars at specialist auction. Unsigned platinum pieces from the same era, if well-designed and in good condition, still bring strong prices. The combination of platinum, original early 20th-century design, and maker's mark is the trifecta that drives the highest prices in inherited fine jewelry. Always photograph every mark carefully and document the stones — the smallest signature can change everything.
Platinum-topped pieces
Some late 19th and early 20th-century jewelry combined platinum with gold: platinum on the visible face for color and strength, gold on the back to reduce cost. These pieces may carry both platinum and gold marks or a single combined mark. They are legitimate mixed-metal pieces and are evaluated on their own terms. Platinum-topped Victorian and Edwardian jewelry can be valuable, particularly when the stones are fine or the design is signed.