The 50 pesos "Centenario" is a bullion coin holding 37.5 g of pure gold at 900/1000 fineness, so its value tracks the daily spot price almost exactly. What varies between French buyers is not the metal price, which is public and identical for everyone, but the buyback rate they pay as a percentage of that spot value.
The 50 pesos was struck by Mexico from 1921 to mark the centenary of independence, then restruck for years afterwards. Its value rests on hard specifications rather than rarity.
Because millions were minted, the ordinary Centenario carries little numismatic premium: it is treated as bullion. Its worth is essentially its fine gold weight multiplied by the current spot price. A rare date or an exceptional grade can add a collector premium, but a standard restrike does not.
The spot price is public and identical for all buyers; the difference lies in the margin. A dealer buys below spot and resells above it, and the gap is their buyback rate expressed as a percentage of the metal's value. Nothing obliges a buyer to publish that rate, which is why two shops can quote very different sums for the same coin on the same day.
For a recognised, liquid bullion coin like the Centenario, margins are usually tighter than for scrap jewellery, because the buyer can resell it easily and knows its exact gold content without assaying. Ask each buyer what percentage of spot they pay, and check the coin is weighed and its fineness confirmed in front of you. You can compare gold buyers in your city to see who is most transparent about their rate.
French law makes the transaction traceable and taxed. Payment cannot be made in cash: the buyer must pay by bank transfer or cheque. You must show valid ID, and the buyer records the sale in a police register kept for the authorities.
Two tax regimes apply to precious metals. By default a flat tax on precious metals is levied on the sale price. Alternatively, if you can prove the original purchase price and date with an invoice, you may opt for the capital-gains regime, which allows an allowance for years of ownership and can reach full exemption over time. Keep any purchase paperwork: without it, the flat tax applies automatically.
Each Centenario contains 37.5 g of pure gold at 900/1000 fineness, with a gross weight of about 41.7 g. The remaining metal is copper, added for durability.
For standard dates, no. It was minted in large numbers and trades as bullion, so its value is essentially its fine gold content at the day's spot price. Only rare dates or top grades add a collector premium.
No. French law forbids cash for precious-metal sales. Payment must be by bank transfer or cheque, you must present ID, and the buyer logs the sale in a mandatory police register.