Alfonso XIII's gold coin doubles in value over a decade

A pendant solder ruins the value of a Charles III escudo

A Charles III escudo from 1787, minted in Madrid, with intact edge reeding and notable preservation, held its value until someone looked closely at its rim. There it was: a small soldered ring. The coin had spent years hanging from a necklace. This minuscule addition disqualifies it from the numismatic market. It remains silver from 1787; it ceases to be a collector's item, and with it, the premium that its antiquity had earned vanishes.

The rule is harsh and simple: condition reigns supreme, not history. A scratch or a dent can cost more than half a century.

Alfonso XIII's gold coin doubles in value over a decade

The 100 peseta coin of Alfonso XIII from 1897 is the market benchmark. The last recorded sale in Extremely Fine (EBC) condition reached €1,917. Ten years earlier, that same piece was bought for €1,000. This isn't inflation: it's gold with structural demand and an issue that was never enormous.

From that mintage, 149,762 coins were produced, compared to 810 in 1961 and 6,000 in 1962. These figures are in the Guerra catalogs and are what collectors use to know the true cost of completing a series. The short answer: increasingly more.

How much does a coin's price change based on its quality?

Enormously, and that's where the profit lies. A 5 peseta coin from the Provisional Government of 1870 in Very Fine Plus (MBC+) is around €45; the same coin in Extremely Fine Plus (EBC+) goes for €300. An Amadeo I from 1871 jumps from €45 in MBC+ to €700 in Superb Specimen Minus (SC-). The difference isn't the metal: it's how much shine it retains and how many marks it withstands under magnification.

• 5 Ptas. Provisional Govt. 1870 (EBC+): €300
• 5 Ptas. Amadeo I 1871 (SC-): €700
• 5 Ptas. Alfonso XII 1885 (EBC+): €150
• 1 Peso Alfonso XIII 1897 (EBC+): €180

Those who cannot distinguish these qualities buy blindly. The price breakdown by year, mint, and star circulates among enthusiasts, and it shows where the real money is.

The FNMT's re-strikes: coins or medals?

In 1961 and 1962, pieces of Alfonso XIII were re-struck. For some in the sector, they were never actual coins: they were allegedly commissioned by a private Swiss company, without any law or decree to support them, and the National Currency and Stamp Factory (Fábrica Nacional de Moneda y Timbre) has no documentation cataloging them as such. The consequences are seen in the prices: a '97 piece in EBC is valued at €1,917, while a re-strike has been seen to close at €1,420.

The controversy transcends economics. It explains why modern Spanish coins are barely collected outside Spain.

The auction house's 18% and gold at spot price

Buying well is as complicated as selling. Leading auction houses add around 18% on top of the hammer price, and not all unsold lots can be acquired afterward. On the gold side, the reference is different: seven French 20 franc coins and one English sovereign totaled 40.635 grams of gold, and their real value is that of the metal, the spot price, not the beauty of the engraving. Hence the repeated advice: sell little by little and distrust anyone who buys large lots without having seen the piece first.

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And then there's the fine print of Spanish collecting: there were issues of 12 coins from the Provisional Government and 87 from Amadeo I of which none remain. They were minted and disappeared. No one knows how many were melted down, but they do know how many are still being sought.