Define the question before selecting a source
Each note addresses a specific comparison problem. We prefer official definitions and methods from bodies such as LBMA, FTC, ECB and EIA. Commercial pages can inform a search-result sample, but are not evidence of live prices or universal premium ranges.
Three kinds of numbers
A real observation needs a source, timestamp, unit, currency and scope. This edition publishes no current market quotations. Every worked numerical example is hypothetical. Formulas and deductions explain a mechanism; they are not fabricated market samples. Unknown fields remain unknown.
Do not mix price categories
Benchmarks, theoretical metal values, retail prices, buyback offers and effective exchange ratios retain their definitions. Jurisdiction and geography are explicit: FTC labeling guidance and EIA gasoline methodology are U.S.-specific, not automatically global rules.
Freshness and update discipline
20 September 2026 is the source-review date for this edition, not the observation date of every source value. Changes to methods, licensing or publication calendars call for a new review. There is no automatic-update promise; rebuilding the website is not an editorial update.
Links, licenses and evidence
Source-bearing factual statements link to numbered public references. Public access does not imply unrestricted redistribution rights. We link to methodology rather than reselling or mirroring licensed live feeds. Search-result samples are not search volumes, keyword difficulty or our ranking data.
Uncertainty and corrections
We do not fill evidence gaps with invented facts. These notes contain no verified dealer offers, consumer interviews or universal premium ranges. Material corrections should identify what changed and why instead of merely refreshing a date. This is the first candidate edition; there is no published correction history yet.