A diecast lorry can look perfect from three feet away and still be a poor buy. Under a shop light, with a torch angled across the cab roof, the story changes: a ridge of thick paint along a masked line, a decal sitting proud of a rivet, four shiny wheels on a truck that has clearly done a hundred thousand imaginary miles. Grading is mostly about slowing down and knowing where to look.

Agree on what the words mean before you talk money

Sellers describe condition with loose language. "Mint" might mean untouched since the factory or simply "not broken". "Excellent" can cover anything from a faint scuff under the bumper to chrome worn to grey. Before you discuss price, ask for specifics: has it been repainted, are all parts original, does the box belong to this model, are there cracks in the plastic hubs or crazing in the tyres.

For online listings, put those questions in a message so the answer is written down. Ask for photographs of the underside, the base stamp and the box corners. A seller who refuses an underside shot is telling you something useful.

Paint: read the finish, not the colour

Factory paint is thin, even and sharp at panel edges. Repaints are thick, slightly soft and usually visible in one of three places: the panel gaps, the window edges, or the underside of the cab. Tilt the model so light rakes across a flat surface. Original paint keeps a consistent sheen; a repaint often shows orange-peel texture, brush marks or a faint colour shift from panel to panel.

Three repaint tells worth memorising

• Overspray. Look on the glass, the tyre sidewalls, the base and the inside of the wheel arches. Paint where it should never be is the clearest sign of a home job.
• Paint in the panel gaps. Doors, bonnets and grille surrounds should have crisp, unpainted seams. Filled seams mean someone sprayed a whole body.
• Uneven wear. A genuinely used model wears where hands and surfaces touch it. A repaint hides that wear, so the chips look fresh while the tyres look twenty years old.

Whites, metallics and pale greys are the hardest to match, which is why half-finished "restorations" so often appear in those colours.

Decals and printed lettering

Factory printing is registered neatly: the text sits square to the panel, layers line up, and fine print stays legible under magnification. Replacement decals usually betray themselves with a visible carrier film edge, a slightly wrong shade, or a font that is close but not right. Run a fingertip lightly over the area. A decal you can feel as a distinct step is probably not original.

Also check for coverage. Printing is normally applied before final assembly, so it should not run across a rivet head, a screw or a moulded seam. Fleet names, registration plates and operator logos vary by market, so compare against a catalogue photograph or a collector reference before accepting a seller's claim that a livery is rare. Some combinations genuinely are; many are simply incorrect.

Wheels, tyres, chassis and the small parts

Wear should be consistent across the whole model. One clean wheel on an otherwise tired lorry is a warning sign, not a bonus. Check that all wheels match each other in style and colour, that plastic hubs are free of hairline cracks, and that axles are straight rather than bent from a fall. On older models, steel axles can rust and rubber tyres can harden, crack or go glossy with silicone dressing.

Now work along the underside. Missing mirrors, exhaust stacks, mudflaps, tank straps, aerials and fifth-wheel parts are all common casualties, and replacements are not always available. Look for glue strings, sanding marks and non-original screws where a factory rivet should sit. Undisturbed rivets matter: drilled, flattened or mismatched rivets suggest a model that has been apart, and taking a diecast lorry apart rarely improves it.

Boxes, inserts and paperwork

A good box can add real value, but it must be the right box. Reproduction packaging is increasingly convincing: the cardboard feels too crisp, the printing too bright, the cellophane too clear. Original boxes usually carry a period price sticker, shop stamp, slight fading or shelf wear, and a printed code that matches the model inside. Compare the code on the box with the base stamp.

Check the insert or inner tray, any catalogue slip or collector card, and whether the box has been repaired with tape or damp-stained. Also ask yourself whether an early box is being paired with a much later casting. That happens more often than sellers admit.

Fakes, recasts and invented colourways

Most deception in this hobby is modest: a repainted playworn model offered as a rare colourway, or a recast sold as an original. Resin copies feel noticeably light in the hand and lack the faint ring of diecast metal. Look closely at the base stamp. Manufacturer names, country of origin, scale and catalogue numbers should be crisp, correctly spelled and in a font that matches known examples of that casting.

Buy the model, not the story. If a seller cannot explain where a "one-off" came from, the price should reflect that uncertainty, not the fantasy.

What counts as a fair price

Compare against completed sales, not asking prices. Asking prices are wishes; sold prices are evidence. Search the same casting in similar condition and note what actually changed hands over the last few months, then add for original box and paperwork. A rare variant in honest playworn condition is often worth less than a common one in mint boxed condition, and repaints in rare colours are worth less still.

At fairs, arrive early, carry cash, ask to handle the model, and check three or four stalls before committing. Dealers expect offers, especially late in the day. Online, insist on your own requested photos rather than stock images, ask about returns, and use a payment method that leaves a record. Set a ceiling before you start looking and treat it as final.

Values shift with fashion, and no one can promise what any model will be worth later. If you are spending serious money, get an independent opinion from an experienced specialist dealer or valuer before you commit.

The five-minute field check

1. Tilt the model under a torch and look for overspray, ridges and paint in the panel gaps.
2. Check decal registration, font and edges; feel for a step with a fingertip.
3. Confirm all wheels match and hubs, tyres and axles are sound.
4. Turn it over and inspect the base stamp, rivets, glue and missing small parts.
5. Match the box code to the model and check for reproduction printing.
6. Compare against recent sold prices, then decide or walk away.

Carry a small torch and a magnifier, take your time, and never let a seller's enthusiasm set your budget. The best purchases in this hobby are the boring ones: honest models, sensibly priced, bought with both eyes open.

Photo: RDNE Stock project / Pexels