Frequently Asked Questions

General

What is the Sovereign Classification Engine?

The SCE is an independent, non-commercial reference platform that provides objective, reproducible classifications for gold sovereign coins minted from 1817 to the present day. It assigns both a Scarcity Rating and a Recognition Status to every coin in its universe.

How many coins are classified?

The current universe contains 783 classified issues spanning all denominations (quarter, half, full, double, and five-pound sovereigns) across all mints (London, Sydney, Melbourne, Perth, Ottawa, Pretoria, Bombay, and Delhi).

Is this a price guide?

No. The SCE is strictly a classification system based on numismatic evidence. It does not provide valuations, price estimates, or investment recommendations. Scarcity is one factor that may influence value, but many other factors (condition, provenance, market demand) are outside our scope.

Scarcity Ratings

What do the scarcity ratings mean?

The five scarcity bands reflect how difficult a coin is to obtain:

• Common — Readily available in the market
• Scarce — Available but requires some effort to locate
• Rare — Infrequently offered; may require patience
• Very Rare — Seldom encountered; specialist knowledge needed
• Extreme Rarity — Exceptionally difficult to acquire; few known survivors

Why are there different thresholds for Circulation and Proof coins?

Proof coins are produced in fundamentally different quantities and contexts compared to circulation strikes. A mintage of 5,000 for a proof issue is relatively common in that context, whereas the same figure for a circulation sovereign would indicate genuine rarity. Separate thresholds ensure fair comparison within each production category.

What is Survival Evidence (SE)?

SE captures independent evidence about how many coins actually survive today, as distinct from how many were originally produced. Many sovereigns were melted, lost, or exported, meaning survival rates can differ dramatically from mintage figures. The Marsh rarity ratings are the primary SE source.

Can SE make a coin less rare?

No. SE can only override PE in the more restrictive direction. If PE already assigns a higher rarity than SE would suggest, PE stands. This conservative approach ensures that coins are never under-classified.

Recognition Status

What is Recognition Status?

Recognition Status captures whether a coin is acknowledged as numismatically significant beyond its basic date-mint identity. It is independent of scarcity — a common coin can be a Key Date, and a very rare coin can be a Standard Issue.

How does a coin qualify as a Key Date?

A coin qualifies as a Key Date through one of two pathways:

• Pathway 1: Explicitly identified as a key date in two or more authoritative references (Marsh, Spink, PCGS, etc.)
• Pathway 2: The inaugural issue of a new series type (e.g., the first modern sovereign of 1817)

What is a Recognised Type?

A Recognised Type is a coin that has been acknowledged as a distinct type within the sovereign series — either by inclusion in a registry set or by identification as a distinct type in two or more authoritative references.

Framework and Governance

What does "frozen framework" mean?

The fv_002 framework is locked. This means that the PE thresholds, SE mapping, recognition pathways, and benchmark definitions cannot be altered without a formal governance review. This ensures that classifications remain stable and trustworthy over time.

Can new coins be added?

Yes. New issues can be added to the universe and classified under the existing framework rules. However, existing classifications cannot be changed without a framework version increment.

What are benchmark coins?

Nine benchmark coins are permanently locked under fv_002. They span the full range of scarcity ratings and recognition statuses, and their expected classifications are validated on every build. They serve as regression tests ensuring the engine's correctness.

Data and Accuracy

Where do mintage figures come from?

Mintage figures are sourced from official Royal Mint records, Marsh's The Gold Sovereign, and other authoritative references. Where sources disagree, the most conservative (highest) figure is typically used.

I think a classification is wrong. What should I do?

If you believe a classification contains an error, please contact us at sce@ingeno.app with the specific coin, the issue you've identified, and any supporting evidence. All corrections are reviewed through our governance process.