| Stainless Steel |
Approximately 2–6 g, depending on thickness and design. |
Usually smooth and rounded when properly polished. Avoid stamped charms with sharp corners, burrs, or unfinished cut edges. |
Low to moderate |
Generally low risk. Some stainless-steel alloys contain nickel, which may irritate cats with a metal sensitivity. Avoid unknown coatings that may flake. |
Strong, corrosion-resistant, and easy to clean. Usually suitable for everyday use. |
A durable everyday charm with a clean appearance. |
Very good |
| Aluminum |
Approximately 0.5–2 g, making it one of the lightest metal options. |
Soft metal can be formed with smooth edges, but thin stamped pieces may develop sharp bends or burrs. Anodized surfaces are preferable to poorly applied paint. |
Low to moderate |
Elemental aluminum is generally considered low concern in normal external contact. Risk increases if paint, plating, or unknown surface treatments chip or are licked. |
Lightweight but easier to scratch, bend, or dent than steel. Keep the surface intact. |
Small cats, kittens old enough to wear a collar, or cats sensitive to collar weight. |
Good when well-finished |
| Titanium |
Approximately 1–4 g for a small thin charm. |
Can be polished to a smooth, rounded finish. Check drilled holes and attachment points for roughness. |
Low |
Typically low allergy risk and widely used in biocompatible applications. The base metal may be safer than an unknown decorative coating. |
Strong, lightweight, and highly corrosion-resistant; usually more expensive than common charm metals. |
Owners seeking a lightweight, durable, low-allergen metal. |
Excellent |
| Sterling Silver |
Approximately 2–7 g for a small charm. |
Usually smooth when polished, but thin designs may bend and expose sharp edges. Tarnish itself is not usually dangerous, but rough oxidation or damaged plating should be avoided. |
Low to moderate |
Sterling silver contains mostly silver with a small amount of alloy metal, commonly copper. Avoid pieces with unknown solder, plating, or decorative paints that could contain unwanted metals. |
Attractive but relatively soft and prone to tarnishing. Clean with a pet-safe method and inspect regularly. |
Decorative use when the charm is smooth, solid, and well-finished. |
Good with quality control |
| Brass or Copper |
Approximately 3–8 g for a small charm. |
Can be smooth when polished, but tarnish, rough engraving, or sharp stamped edges may cause rubbing. |
Moderate |
Direct contact may cause skin irritation in sensitive animals. The main concern is poorly controlled alloys, solder, plating, or paint that may contain lead or other unwanted metals. Do not use products with unknown composition. |
Durable but tarnishes and may leave discoloration on fur or skin. Requires regular inspection. |
Occasional decorative wear only when the metal composition and finish are documented. |
Use caution |
| Acrylic or Hard Plastic |
Approximately 0.5–3 g, depending on thickness and hardware. |
Lightweight and capable of rounded edges, but cracks, chips, and sharp corners can develop after impact. Avoid brittle or damaged pieces. |
Low |
Risk is generally low when made from a reputable, pet-safe material. Paint, glitter, adhesives, and unknown additives can be licked or shed if the surface deteriorates. |
Light and colorful but may scratch, crack, or fade. Replace immediately if chipped or split. |
Quiet, lightweight identification or decorative charms. |
Good if intact |
| Silicone or Soft Rubber |
Approximately 1–4 g, excluding the attachment ring. |
Soft, flexible, and generally comfortable when free from thin tearing edges. Inspect for bite marks, splits, or loose fragments. |
Very low |
Usually low concern when made from a clearly specified, pet-safe formulation. Avoid products with a strong chemical odor, unknown softeners, peeling coatings, or loose pieces. |
Quiet and flexible but can collect dirt and may be chewed or torn. Wash and inspect frequently. |
Cats that dislike jingling sounds or hard objects. |
Very good if undamaged |
| Wood |
Approximately 1–5 g, depending on species and thickness. |
Must be finely sanded and sealed with a non-toxic, fully cured finish. Splinters, rough grain, and sharp drilled holes are unacceptable. |
Low |
Untreated wood may be relatively low concern, but stains, varnishes, glues, and sealants can introduce irritation or ingestion risks. Avoid unknown finishes. |
Can absorb moisture, swell, crack, or splinter. Keep dry and replace at the first sign of damage. |
Quiet, natural-looking charms used with careful inspection. |
Moderate |
| Enamel-Coated Metal |
Approximately 3–8 g, including the metal base and coating. |
Smooth when intact, but chips can create sharp edges. Inspect the rim, back, drilled hole, and attachment loop. |
Moderate |
The underlying metal and coating composition matter. Avoid pieces with chipped paint, exposed unknown metal, or decorative coatings that flake when scratched. |
Attractive and fairly durable, but impact can chip the finish. Remove if the coating begins to deteriorate. |
Decorative designs when the coating is documented and undamaged. |
Good with regular checks |