Choose chemically stable holders
Use inert holders intended for long-term numismatic storage. Avoid soft vinyl containing PVC, household tape, acidic paper, rubber bands, and unknown plastics that can stain or corrode surfaces.
Control the environment
Keep temperature and humidity stable, limit exposure to pollutants and salt air, and store coins away from flood risk. Silica gel can help in a closed container when it is monitored and renewed correctly.
Handle only when necessary
Hold raw coins by the edge over a clean, soft surface. Avoid fingerprints, wiping, dipping, polishing, and attempts to remove toning or residue without conservation expertise.
Preserve records with the object
Keep acquisition date, seller, price, provenance, certification number, photographs, and identifying notes. Back up the record separately from the physical collection.