Gold Sovereigns: Composition, Dimensions, Dates and Mint Variants

British full sovereigns, branch-mint issues and modern Perth Australian sovereigns • Updated 8 September 2026

A gold sovereign’s fineness is easy to state. Its complete composition is not.

The modern British sovereign is a 22-carat gold coin: nominally 91.6667% gold by mass. The remaining approximately 8.3333% is the part that requires closer attention. Silver and copper are not interchangeable additions, and the balance between them has not been constant throughout the sovereign’s history.

For dealers, numismatists and authentication specialists, the essential distinction is between gold fineness, complete alloy composition and the characteristics of an individual coin. A catalog entry that says “gold .9167” establishes neither an exact silver/copper recipe nor an identical acoustic response across all coins assigned to that entry.

This reference identifies the principal full-sovereign types, their date ranges and Numista IDs, and the composition distinctions supported by the cited evidence. Where a complete recipe has not been established, it is identified as such—not replaced with an assumed copper balance.

Scope and conventions

The core series is the British full sovereign introduced in 1817, including its historical branch-mint issues. Modern Perth Mint Australian $25 sovereigns are included separately.

Date ranges describe the bounds of a catalog type. They do not imply uninterrupted annual production or that every mint struck every date. Overlapping ranges are intentional where portraits or reverse types coexisted.

All composition percentages are by mass. “22ct” denotes the nominal gold standard; it does not certify the composition of an individual specimen. Small differences in catalog notation—such as .9166, .9167 and .917—are not, by themselves, evidence of different alloy formulations.

This is a type-level reference, not an exhaustive inventory of die varieties, privy marks, special finishes, patterns or every coin worldwide bearing the name “sovereign.”

Diameter and thickness: how to read the specifications

The Royal Mint gives 22.05 mm as the standard full-sovereign diameter. Its denomination reference does not state a numerical thickness. Consequently, the tables below reproduce catalog-reported dimensions from each linked Numista entry, rather than supplying a universal thickness or silently replacing every diameter with the modern nominal standard. — means no thickness was established from that entry, not zero. Royal Mint: sovereign sizes and weights.

Mint-published dimensions provide these additional reference points:

Maximum thickness, catalog thickness and the thickness of the coin’s central field are different descriptions. The source wording should be retained. An unspecified catalog thickness must not be treated as an independently verified rim measurement, manufacturing tolerance or uniform body thickness. Nor do entries rounded to 22 mm versus 22.05 mm, or 1.5 mm versus 1.52 mm, establish an intentional dimensional change.

Dimensional discrepancies requiring caution

A dagger † in the tables flags a value requiring particular care:

• Numista lists diameters of 22.5 mm for Sydney type I, 21.5 mm for the Australian young-head shield type, and 23 mm for the Australian Jubilee type. These are reproduced as catalog entries, not endorsed as proven departures from the sovereign standard. N24196, N24198, N28487.
• For the 1920 Perth sovereign, Royal Mint gives 22.05 mm, whereas Perth Mint’s historical-coin product page gives 21.50 mm maximum. The discrepancy remains unresolved; it is not evidence that two diameter variants existed. Royal Mint 1920 P specification, Perth Mint 1920 specification.
• Numista’s 1 mm thickness for Edward VII Ottawa sovereigns and 1.25 mm for Australian small-head George V sovereigns differ materially from other entries. Neither is presented here as a verified manufacturing change; measurement location and provenance need confirmation. N22058, N115428.

For specimen assessment, record the measurement method and locations as well as the result. A published catalog value is not, on its own, an authentication acceptance limit.

The alloy changes that matter

Sydney: the critical transition is within 1868

Early Sydney sovereigns were made from naturally silver-rich Australian gold. The Perth Mint’s historical account places the experimental introduction of Miller’s refining process at Sydney during 1868, with the change reflected in coins of that date. The relevant boundary is therefore metallurgical, not the later replacement of the Sydney reverse design.

For classification, distinguish early silver-rich issues, the transitional 1868 population and subsequent issues. These are historical groupings, not certified recipes for every specimen. In particular, the evidence does not justify describing the entire non-gold fraction of every early Sydney sovereign as pure silver. Perth Mint: the 1868 Sydney sovereign and refining.

The catalog consequence is important: Numista N6331 spans 1857–1870 and therefore crosses the transition. A coin’s Numista ID—and, for 1868, its date alone—cannot determine its complete alloy. Numista N6331.

London: historical gold was not one fixed binary alloy

Published first-hand XRF observations illustrate why “91.67% gold, 8.33% copper” should not be applied indiscriminately to historical sovereigns.

These are measurements of selected specimens, not official recipes for the corresponding years. XRF characterizes the analyzed surface region; it does not establish a certified bulk composition for an entire issue. A reported zero is also not proof of absolute elemental absence.

Nevertheless, the observations are sufficient to reject two sweeping rules: that all historical London sovereigns were binary gold/copper alloys, and that negligible-silver alloys began only in 2000. Chards: original sovereign XRF analysis.

Royal Mint: 2026 is a documented modern boundary

The Royal Mint identifies 2025 as the final year of its rose-gold sovereigns and 2026 as the return to yellow gold. This is a documented product change and should be retained in professional classification. It is not a change from 22-carat to a different gold fineness.

The cited mint announcement does not establish exact silver and copper percentages. An equal split of the non-gold fraction should therefore not be presented as the official formula without a separate specification. Royal Mint: 2025 sovereign collection announcement.

The 2026 bullion and collector issues also have separate catalog entries: N526743 for bullion with security features and N531761 for proof and related special strikes. Their shared yellow-gold designation should not erase those product distinctions. Numista N526743, Numista N531761.

British sovereigns: type and composition reference

In the following table, “exact Ag/Cu balance unestablished” means that this reference has not identified a complete formula applicable to the whole catalog type. It does not mean that every coin within that type necessarily differs.

The linked Numista entries document catalog identity, date bounds and nominal fineness. They are not mint-issued alloy certificates.

The 1887 London Jubilee issue merits particular care when investigating historical alloy claims. A recipe attributed to one year, mint or design must not be extended automatically to all Jubilee-head sovereigns. This reference does not assign an exact special recipe to the entire type.

Dates on coins are not always production dates

The best-known example is the London sovereign dated 1925, which was also struck in 1949, 1951 and 1952. An inscription of 1925 is therefore insufficient to identify the actual production year. Royal Mint: 1925 George V sovereign.

Other useful qualifications:

• Gillick-portrait sovereigns were issued in 1957–1959 and 1962–1968, rather than every year in the overall range. Numista N11461.
• Production of 1974-dated sovereigns continued into 1975 at Tower Hill; the 1976 issue belongs to Llantrisant production. A mint-location change is not itself evidence of an alloy change. Numista N12812, with references to Royal Mint annual reports.
• The 2026-dated proof type was released in November 2025. Purchase year and coin date should not be confused. Numista N531761.

Historical branch mints and modern Indian issues

Mint marks identify production origin: S for Sydney, M for Melbourne, P for Perth, C for Ottawa, I for Bombay and SA for Pretoria. Modern Indian I-mark issues belong to a separate production era from Bombay’s 1918 sovereign.

A shared sovereign standard does not establish a documented, identical silver/copper balance across these mints. Conversely, a different mint mark does not prove that the alloy was different.

A 1920 Perth sovereign, for example, belongs to N22076 and carries the P mint mark. Its nominal gold standard is established, but the linked catalog record does not establish a precise 1920 Perth silver/copper recipe. It should not acquire one merely by borrowing the specification of another 22-carat coin. Numista N22076.

For the 1929–1932 Pretoria type, the table preserves Numista’s explicit gold/copper formulation while identifying its evidence level. A catalog statement and an independently verified mint specification are different forms of evidence. Numista N27532.

Modern Perth Australian sovereigns are a separate series

“Perth sovereign” can refer to two different populations: historical British sovereigns struck at Perth, or modern Australian legal-tender sovereigns produced by the Perth Mint.

For its 2026 Australian $25 sovereign, Perth specifies 91.67% gold, a minimum gross mass of 7.988 g, and a maximum diameter of 22.55 mm. The cited specification does not disclose the silver/copper balance. Those dimensions and product identity must be retained rather than substituting a British sovereign specification. Perth Mint: 2026 Australian sovereign.

The 2022 issue is platinum-plated gold, not a bulk platinum sovereign. Its coating is a distinct feature that should remain in the description even though the underlying coin is 22-carat gold. Numista N332243.

No full-sovereign entries for 2006–2008 or 2023 have been verified for this table. A gap in the table should not be filled by assuming annual production.

What composition tells us—and what it does not

For professional use, three evidence levels should remain separate:

A defensible description may therefore be “22-carat gold; complete silver/copper balance not established.” That is more precise than supplying an unsupported numerical formula.

The same distinction matters for acoustic testing. Alloy composition can affect resonance, but an alloy label is not an acoustic reference on its own. Dimensions, mass distribution and the condition of the coin must also be considered. A shared nominal fineness is not sufficient grounds to assume a shared ping, and a change in catalog type is not proof of a measurable acoustic difference.

For authentication records, preserve the issuer, denomination, coin date, mint mark, design and finish, together with any documented production-era distinction. Treat analytical results as specimen evidence unless their applicability to a wider issue has been established. A ping result should be interpreted alongside other authentication evidence, not as a complete metallurgical assay.

Coins outside this reference

Fractional and multiple sovereigns, piedforts and pre-1817 hammered issues require separate treatment. So do sovereign-named coins issued by other jurisdictions.

The name alone does not guarantee either 22-carat gold or the mass of a British full sovereign. For example, Numista records Gibraltar’s 2002 boat-on-Thames sovereign at 37.5% gold and 6.22 g. It is not a standard British full sovereign despite its denomination. Numista N404059.

The professional conclusion

The sovereign is a durable monetary standard, not a single timeless alloy recipe.

Its principal types and mint origins can be cataloged with confidence. Some metallurgical boundaries—notably Sydney’s 1868 transition and the Royal Mint’s 2026 return to yellow gold—are documented. A complete year-by-year, mint-by-mint silver/copper schedule is not established by the sources cited here.

The sound reference practice is to preserve those distinctions: state the known fineness, identify the issue precisely, document the evidence for the alloy, and leave unsupported percentages unstated.