More value is lost to careless storage than to careless buying. Damage to a coin surface cannot be undone, and a collector who learns this early keeps everything they buy.

Three rules cover most of it.

Rule one. Do not touch the surface

Skin leaves oil and salt. On a proof coin the mark appears within days and it is permanent.

Hold a coin by the edge, between thumb and forefinger, over a soft surface. Better still, leave it in its capsule or card and never take it out. A coin in original sealed packaging is worth more than the same coin handled once.

Cotton or nitrile gloves are worth using for anything valuable.

Rule two. Never clean a coin

This is the most expensive mistake in collecting, and it is made with good intentions.

Cleaning removes the original surface. It leaves fine scratches and an unnatural brightness that any experienced buyer recognises immediately. A cleaned coin routinely sells for a fraction of an untouched one, and toning that looks like tarnish is often desirable and adds value.

No polish. No cloth. No toothpaste. No ultrasonic cleaner. No dip. Leave it alone.

Rule three. Keep it dry, dark, stable and away from plastic that leaks

Coins want cool, dry, dark and steady. Temperature swings and humidity are the enemies, which rules out garages, sheds, roof spaces and bathrooms.

Silver tarnishes in the presence of air, moisture and sulphur. Copper reacts fastest of all.

The serious hazard is PVC. Soft flexible plastic sleeves and wallets, particularly older ones, release chemicals as they age and leave a green sticky film that eats into the coin. Anything soft and floppy should be treated with suspicion. Use inert materials only.

What to store coins in

Capsules. The best single purchase a new collector makes. A rigid clear shell that seals the coin away from air and hands. Match the capsule size to the coin diameter. Round capsules come in twenty-one millimetre and twenty-five millimetre sizes for Australian $2 and $1 coins respectively.

Coin holders. Card holders with a clear window, for volume storage of circulating coins. Self-adhesive versions are quick. Staple versions are more secure and do not rely on adhesive that ages.

Coin boxes. Trays sized for capsules, so a run of coins sits together and can be looked at without handling. Lighthouse Coin Box with forty-eight round capsule spaces for $2 coins (/products/lighthouse-coin-box-48x-21-5mm-capsule-spaces) at fifty-five dollars.

Albums. Best for a series being built over years, and the easiest way to see a gap. Renniks Coin Album Black (/products/renniks-coin-album-black) at forty-one dollars ninety-five, with refill pages available in twenty, thirty, forty-two and sixty-three pocket layouts.

A magnifier. Not storage, but the tool that makes collecting more interesting. Lighthouse Pocket Magnifier 7x LED (/products/lighthouse-pocket-magnifier-7x-led-35mm) at thirty-four dollars ninety-five.

Original packaging

Keep it. All of it. The case, the certificate, the outer sleeve and the box.

For proof coins the packaging is part of the item. A proof coin without its certificate is worth noticeably less than the same coin complete. Store the paperwork flat and dry, with the coin rather than in another room.

Do not open sealed rolls or sealed sets unless there is a reason. Sealed is a condition, and it is one that cannot be restored.

Insurance and records

Photograph each coin, front and back, and note what it is, what was paid and when. Keep the file somewhere other than the house that holds the collection.

A collection above a few thousand dollars is worth mentioning to an insurer, because household contents cover often caps collectables well below their value.

Mint Coin Shop stores stock in smoke-free conditions and packs every order for protection in transit. Insurance and signature on delivery can be added at checkout, and are worth taking on anything valuable.