25 Euros Evolution

Austria's bimetallic niobium-silver series, running since 2003, assigns a distinct anodized color to the niobium core each year — the 2014 "Evolution" issue uses a green tint achieved through controlled oxide layering on the metal's surface, not paint or coating. Each year's color is unique and unrepeatable once the anodizing parameters are set, which makes cross-year color matching for sets a known frustration among collectors. The Austrian Mint holds the process closely.