1. Historical context

In 1986, Portugal issued commemorative coins linked to the FIFA World Cup held in Mexico. The 100 Escudos coin was created to mark the XIII World Football Championship (Mexico 1986) and was produced by the Portuguese Mint (Imprensa Nacional — Casa da Moeda, INCM). It was intended as a commemorative piece rather than regular circulation currency.

2. Physical characteristics (description)

General features (depending on the variant):

• Obverse: the inscription REPUBLICA PORTUGUESA, the year 1986, and the face value 100 ESCUDOS.
• Reverse: inscriptions related to the event — XIII MUNDIAL DE FUTEBOL and MEXICO 86.
• Edge: reeded.
• Mint: Imprensa Nacional — Casa da Moeda, Lisbon.

3. Known variants

There are at least two widely recognized variants:

1. Copper–nickel (common version) — often listed as KM #637

• Composition: copper-nickel
• Weight: approx. 16.5 g
• Diameter: approx. 33–34 mm
• Large mintage and the most common version found in the market.

2. Silver .925 (collector version / non-circulating / proof) — often listed as KM #637a

• Composition: sterling silver (925‰)
• Weight: ~16.5 g
• Diameter: 33.5 mm
• Issued in smaller numbers, including Brilliant Uncirculated and Proof strikes, making it far less common.

4. Mintage and availability

• Copper–nickel version: high mintage, widely available through dealers and online sellers.
• Silver version: much lower mintage, appears less frequently and is more sought after by collectors, especially Proof editions.

5. Numismatic value (price guidelines)

Prices vary depending on variant, condition (circulated, Mint State, Proof), and market platform.

Approximate market ranges:

• Copper–nickel (circulated): generally €1.50 to €15, depending on wear and seller.
• Copper–nickel (uncirculated / MS): typically €10–€20 for well-preserved examples.
• Silver (BUNC/Proof): usually €20–€45, with Proof pieces sometimes reaching higher prices at auctions.

Important: These ranges are indicative. Exact pricing depends on condition, certification, and current demand.

6. Identifying authenticity and condition

• Material and color: copper-nickel has a standard silvery tone; silver pieces have a brighter luster and characteristic weight.
• Weight check: around 16.5 g is expected for both variants.
• Edge and inscriptions: reeded edge and clear lettering help verify authenticity.
• Avoid aggressively cleaned coins: cleaning marks reduce value significantly.
• For higher-value pieces, certification (NGC, PCGS, etc.) or purchase from a reputable dealer is recommended.

7. Tips for collectors / buying & selling

• For thematic collections (football/World Cup), the copper-nickel version is affordable and easy to acquire.
• For investment or rarity, focus on silver, Proof, or certified examples.
• Compare multiple sources (dealers, marketplaces, auctions) to gauge real market pricing.

8. Short conclusion

The 100 Escudos (1986, Mexico 86) coin is an appealing commemorative piece. The copper-nickel version is common and accessible, while the silver KM 637a variant carries higher collector interest and market value. Condition and strike type (especially Proof) have a major impact on price.