Yes, and many collectors consider this a desirable feature. Carbon steel naturally develops a subtle surface patina through controlled oxidation that creates a warm, slightly darker tone compared to a freshly polished surface. This patina is different from destructive corrosion — it forms a thin, stable oxide layer that can actually provide some protection against deeper corrosion. The patina develops character over years of ownership, making the blade increasingly personal and unique. Some collectors actively encourage patina development by allowing gentle, controlled oxidation. Others prefer to maintain the bright polished surface through regular oiling and careful storage. Both approaches are valid collecting practices.