METHODOLOGY AND SOURCE NOTES
Prepared: November 6, 2026. Data through September 2026.

SOURCE
World Bank Commodity Price Data (Pink Sheet), October 2, 2026 edition. Monthly Prices sheet: Gold, Silver and Platinum. Units: U.S. dollars per troy ounce.
Source page: https://www.worldbank.org/en/research/commodity-markets
Workbook: https://thedocs.worldbank.org/en/doc/74e8be41ceb20fa0da750cda2f6b9e4e-0050012026/related/CMO-Historical-Data-Monthly.xlsx
Release PDF: https://thedocs.worldbank.org/en/doc/74e8be41ceb20fa0da750cda2f6b9e4e-0050012026/related/CMO-Pink-Sheet-October-2026.pdf

PROVENANCE
The extraction uses the original workbook snapshot retrieved October 30, 2026, whose internal update date is October 2, 2026. September 2026 endpoint values were independently checked against the official October 2026 PDF on November 6, 2026: gold 4319, silver 64.6, platinum 1784. This does not represent a fresh download of every historical value. The period deliberately ends in September; October observations are not included.
Source workbook SHA-256: ea1c350827878ea3bbe30e3cda16a13fd3bd5b409b8458940dc94a36b5a33154

CALCULATIONS
189 consecutive monthly observations, January 2011 through September 2026 inclusive.
Index(t) = price(t) / price(January 2011) * 100.
Percentage change = (price(September 2026) / price(January 2011) - 1) * 100.
Gold/platinum ratio(t) = gold USD/troy oz(t) / platinum USD/troy oz(t).
Calculations use the available published observations, with no interpolation, currency conversion, rebasing of the source data, or adjustment at source-definition changes. CSV derived columns have eight decimals; chart indices are rounded to integers and percentage changes to one decimal. These additional calculation decimals do not imply additional precision in the underlying prices.

DEFINITIONS AND LIMITATIONS
Monthly average benchmark prices, not end-of-month closes or live executable retail quotes. Nominal USD values; no adjustment for inflation, tax, premiums, spreads, storage, financing, fees or reinvestment. These are price changes, not the total returns of a bar, coin, fund or trading strategy. No forecasts or causal attribution are made.
Gold: spot average of daily rates from June 2025; previously UK 99.5% fine, London afternoon fixing, average of daily rates.
Platinum: 99.95% minimum purity, plate or ingot form, spot average of daily rates from June 2025; previously UK 99.9% refined, London afternoon fixing.
Silver: UK 99.9% refined, London afternoon fixing.
Gold and platinum source definitions changed in June 2025. These official series are retained as published; purity and reference conventions are not identical across metals. The ratio compares reference-price values per ounce, not a transaction that can be executed at that rate.

ENDPOINT SENSITIVITY
January 2011 is the declared common baseline, not a claimed optimal investment date. Different starting months produce different results. For comparison, December 2010 to September 2026 gives gold +210.5%, silver +120.5%, platinum +4.3%; January 2012 to September 2026 gives gold +161.1%, silver +110.4%, platinum +19.0%. The near-flat platinum headline is specific to the chosen January 2011 baseline.

ATTRIBUTION
Underlying data: World Bank Commodity Price Data. Dataset licensing reference: https://datacatalog.worldbank.org/search/dataset/0038238/commodity-prices-history-and-projections (CC BY 4.0; consult source terms). Changes by World Gold: selecting three series and a fixed period, calculating indices, percentage changes and ratios, and designing original graphics. No World Bank endorsement is implied. The underlying data licence does not assign the same licence to World Gold’s article or original graphic design.