ASTM B562 is the standard specification published by ASTM International — formerly the American Society for Testing and Materials — that defines the chemical composition, fineness, and colour classifications of gold and gold-alloy jewellery. Covering 10-karat, 14-karat, and 18-karat grades across the principal commercial colours — yellow, white, green, rose, and red gold — the specification provides manufacturers, assay laboratories, and retailers with a common technical language for describing and verifying gold alloy quality. Although compliance is voluntary in most jurisdictions, ASTM B562 is widely adopted across North America and serves as a de facto benchmark for quality assurance in the regional jewellery trade.

Background and Issuing Body

ASTM International is one of the world's largest voluntary standards organisations, producing technical specifications across industries ranging from construction materials to medical devices. Its jewellery-related standards fall within Committee B02 on Nonferrous Metals and Alloys. ASTM B562 sits alongside related specifications such as ASTM B253 (gold-filled products) and ASTM B605 (electrodeposited coatings of gold) to form a broader framework of gold-product standards. The specification is periodically reviewed and revised to reflect advances in metallurgical practice, changes in alloying-element availability, and evolving trade requirements.

Scope and Karat Grades

The specification addresses three karat grades that together account for the overwhelming majority of gold jewellery sold in North America:

• 10-karat (10K) — a minimum gold fineness of 41.7 per cent (417 parts per thousand). This is the legal minimum for an article to be described as gold in the United States under Federal Trade Commission guidelines.
• 14-karat (14K) — a minimum fineness of 58.3 per cent (583 parts per thousand). The dominant commercial grade in the North American market, balancing durability with gold content.
• 18-karat (18K) — a minimum fineness of 75.0 per cent (750 parts per thousand). Preferred for fine jewellery and in markets where higher gold content is culturally or commercially significant.

The specification does not address 22-karat or 24-karat (fine gold) articles, which are governed by separate considerations and are rarely used in alloyed jewellery applications.

Alloy Colours and Permissible Alloying Elements

ASTM B562 recognises that the colour of a gold alloy is determined by the identity and proportion of the metals added to the gold base. The specification defines permissible alloying elements and their compositional ranges for each recognised colour category.

• Yellow gold — the classical colour, achieved through a balance of silver and copper. Silver imparts a greenish cast; copper introduces warmth. The proportions are adjusted by karat grade to maintain the characteristic yellow hue while meeting fineness requirements.
• White gold — produced by alloying gold with palladium, nickel, or zinc, all of which suppress the yellow colour. Palladium-based white golds are hypoallergenic and increasingly preferred; nickel-based alloys, though harder and less costly, carry a documented risk of contact dermatitis and are subject to restrictions under European Union directives (notably EU Nickel Directive 94/27/EC), though ASTM B562 itself is a North American standard and does not impose such restrictions.
• Green gold — achieved by increasing the silver content relative to copper, producing an alloy sometimes called electrum in its natural form. Cadmium was historically used to intensify the green tone but is now largely excluded from commercial specifications on toxicological grounds.
• Rose gold — characterised by an elevated copper content relative to silver. The warm pinkish-red tone deepens as the copper proportion rises. Rose gold has seen sustained commercial popularity since the early twenty-first century.
• Red gold — an extreme of the rose-gold spectrum, with copper as the dominant alloying element and little or no silver. The resulting colour is a pronounced reddish-copper tone. Red gold is less common in mainstream jewellery but appears in specialist and artisanal work.

Zinc is frequently included in small quantities across several alloy families as a deoxidiser and to improve casting fluidity. Palladium, beyond its role in white gold, may appear in trace quantities in other alloys to refine grain structure.

Mechanical Properties

Beyond chemical composition, ASTM B562 specifies mechanical properties relevant to manufacturing and end-use performance, including tensile strength, yield strength, and elongation. These properties vary significantly between alloy families and between annealed and work-hardened conditions. White gold alloys, for example, tend to be harder and less ductile than equivalent-karat yellow gold alloys, which has practical implications for stone setting and forming operations. The specification's mechanical data allow jewellery manufacturers to select alloys appropriate to a given fabrication process — whether casting, die-striking, rolling into sheet, or drawing into wire.

Relationship to Hallmarking and Legal Frameworks

ASTM B562 is a compositional and performance specification, not a hallmarking law. In the United States, the legal framework for gold fineness marking is established by the National Gold and Silver Stamping Act of 1906 and enforced through FTC guidelines, which require that any karat stamp accurately reflect the article's gold content within defined tolerances. ASTM B562 is compatible with these requirements but operates independently of them. In Canada, gold fineness is governed by the Precious Metals Marking Act, which similarly mandates accurate disclosure but does not require compliance with any specific ASTM standard.

By contrast, the European Union operates under the Common Control and Marking Agreement (the Vienna Convention) and individual national hallmarking systems — the UK Hallmarking Act 1973 being a prominent example — which impose mandatory independent assay and stamping requirements that go beyond what ASTM B562 addresses. Jewellery exported from North America to European markets must therefore satisfy those separate regimes regardless of ASTM compliance.

Role in the Trade and Testing Laboratories

For North American jewellery manufacturers, ASTM B562 serves several practical functions. Alloy suppliers reference the specification when formulating and marketing master alloys, providing assurance that a product described as, for instance, "14K rose gold per ASTM B562" meets defined compositional parameters. Quality-control laboratories — including those operated by major refiners and independent assay houses — use the specification's compositional tables as a reference when verifying incoming or outgoing material by X-ray fluorescence (XRF) spectrometry or fire assay. Retailers and brands sourcing from multiple manufacturers can invoke the standard in purchase specifications to reduce variability across their supply chains.

It is worth noting that XRF analysis, while rapid and non-destructive, measures surface composition and may not fully reflect bulk fineness; fire assay remains the definitive method for fineness determination when legal or contractual disputes arise. ASTM B562 does not itself specify the analytical method to be used for verification, leaving that to the parties involved or to applicable regulatory frameworks.

Limitations and Complementary Standards

ASTM B562 does not address every aspect of gold jewellery quality. Surface finish, dimensional tolerances, gemstone setting integrity, and solder fineness are outside its scope. Solder alloys used in gold jewellery — which must themselves meet fineness requirements under FTC guidelines — are addressed in separate ASTM specifications. Similarly, the standard does not cover gold-filled, gold-plated, or vermeil products, each of which has its own specification or regulatory definition.

Practitioners working across international markets must also be aware that alloy designations under ASTM B562 do not map directly onto ISO or European Norm (EN) alloy designations, and that colour descriptions, while broadly consistent, may differ in precise compositional boundaries from those used by European trade associations such as the World Jewellery Confederation (CIBJO), whose Gold Book provides an internationally oriented counterpart to ASTM's North American framework.

Further Reading

• ASTM International — B562 Standard Specification for Gold and Gold Alloy Jewellery
• US Federal Trade Commission — Revised Jewelry Guides
• Gems & Gemology — Gold Alloys in Jewellery (GIA)