CANVASES, CARATS AND CURIOSITIES

Hallmarking practices have ancient origins, with formalized systems appearing in France in the 13th century and Great Britain during the 14th century. These early marks verified both material purity and maker identity through registered marks, and are relatively easy to decipher if the piece has been well preserved. The practice spread globally, with the United States implementing the National Gold and Silver Stamping Act of 1906, which mandated accurate purity markings. In 1961, further regulations required manufacturers to include makers’ marks alongside purity indicators.

Understanding jewelry marks and signatures is essential for collectors, connoisseurs and enthusiasts. These identifying marks provide critical information about a piece's authenticity, origin, materials and historical context. This guide examines the significance of these marks to help you authenticate and date your fine jewelry.

Precious Metal Marks

Gold Purity Marks

Gold purity is indicated through two primary systems:

• Karat system: Two digits followed by "K" (e.g., 18K)
• Sometimes represented by “AU”, which comes from the Latin word Aurum, meaning gold
• Millesimal fineness: Three-digit number representing parts per thousand (e.g., 750)

Important Note: Jewelry marked with HGE (Heavy Gold Electroplate), GE (Gold Electroplate) or GF (Gold Filled) contains minimal gold content applied over base metals such as copper.

Silver Purity Marks

The term "sterling" appeared in England around the 12th century, and the initial standard was eventually set at 925 parts silver per 1000 (92.5%). Hallmarking was established in London by 1300, requiring the "sterling" standard and enforcement was strict, with substandard pieces destroyed.

Throughout the 19th century, mass production and electroplating disrupted the silver industry, and there was not yet a global standard. Germany, for example, had 800 or 835 parts per thousand, France 800 or 950 and Russia 875. By the early 20th century, though, particularly through the United States’ legislation, 92.5% became a common standard for silver.

Sterling silver (92.5% pure silver) is denoted by:

• "925"
• "STERLING"
• "STG"
• "STER"

Important Notes:

"German silver" or "nickel silver" contains no actual silver and is composed of copper, nickel and zinc.

Platinum Purity Marks

Platinum did not gain prominence in jewelry and luxury items until the late 19th century. Unlike silver, platinum's extreme melting point (1,768°C) made it difficult to work with until modern techniques were developed. When platinum emerged as a luxury metal, various standards were established globally.

Platinum purity is typically marked as:

• "PLAT" or "PT" followed by the fineness number
• "950" (95% pure platinum, common in European pieces)
• "900" (90% pure platinum, historically used in American pieces)
• "850" (85% pure platinum, less common)
• "PT950" or "PLAT950" (modern international standard)

The United States established legal standards for platinum in 1976, requiring items to contain at least 950 parts per thousand pure platinum to be marketed as platinum. Items between 850 and 950 parts per thousand must be marked with their exact fineness.

Important Note: Unlike gold and silver, platinum is rarely alloyed with base metals.

Dating Terminology

Understanding chronological terms is crucial when discussing jewelry:

• Antique: Items over 100 years old
• Vintage: Items over 20 years old
• Retro: Typically refers to mid-century designs (1930s-1950s)

Maker's Marks

Maker's marks identify the jewelry's creator, manufacturer or design house. These distinctive stamps often feature:

• Initials
• Symbols
• Logos
• Registered trademarks

Identifying these marks can trace a piece to renowned designers and houses such as Tiffany & Co., Cartier, Van Cleef & Arpels, and others.

Authenticating Jewelry Through Marks

When examining jewelry marks:

1. Use magnification to clearly view marks
2. Document observed marks
3. Research marks in reference guides or databases
4. Consider consulting experts for rare or ambiguous marks
5. Verify consistency of marks with the piece's apparent age and style

Maker’s Marks You Should Know:

Tiffany & Co.