Scrubbing or polishing your coins can ruin their natural patina and drastically reduce their value. Even light cleaning can cause micro-scratches that collectors avoid.
Using PVC holders, humid areas, or metal containers can lead to corrosion and discoloration. Always store coins in acid-free holders or professional-grade albums.
The oils and dirt from your fingers can leave lasting marks or stains. Use cotton gloves or handle coins by the edges only.
Stacking silver, copper, and other metals together can cause chemical reactions that lead to toning, spotting, or corrosion.
Not knowing or misrepresenting your coin’s grade can lead to undervaluing or overpricing, scaring off serious buyers or collectors.
Commercial coin dips promise shine but often strip away valuable surfaces. This damages the coin's originality and decreases its worth.
Lacking provenance, certification, or proper records can make even rare coins harder to sell or authenticate in the future.