Spotting fakes and undisclosed restoration

Moroccan trilobites are the most restored fossils on the market. Tells: a suspiciously perfect specimen at a low price; filler that is slightly the wrong colour or too uniform under raking light; “eyes” and free cheeks that do not quite align; a matrix that is smooth and sculpted around the fossil rather than broken; a specimen that is warm to the touch or scratches with a steel point where real calcite would not. The famous “trilobite pizzas” are many individuals, often of different species, set into one slab of poured resin-and-rock — legal to sell as a composite, fraud as a “death assemblage”.

Under long-wave UV, most fillers, resins, paints and cyanoacrylate glue fluoresce differently from bone, shell and stone. Restoration on Moroccan mosasaur jaws (teeth glued into carved sockets), on ammonites (resin fill in the body chamber, air-brushed suture lines) and on Green River plates shows as brighter or duller patches with a crisp boundary. A cheap 365 nm torch in a dark room is the single best tool a buyer owns.

Green River plates are commonly “inpainted”: the fish is real but missing fins, a tail or scale detail have been painted on the matrix in fish-coloured pigment, sometimes over a filled area. Look at the plate wet — water darkens matrix but not paint — and under raking light for the flat, brush-textured areas. Reputable dealers describe this as “restoration” and give a percentage; many plates from the tourist trade do not.

Casts and carvings: resin casts have air bubbles, a uniform colour throughout a break, and a plastic sound and warmth; check any hidden surface. Carved “fossils” (sandstone tracks, soapstone eggs, calcite ammonites) show tool marks under the loupe and no internal structure at a broken edge. Dinosaur eggs from China are sold with sculpted eggshell over concretions; look for shell that is the same thickness everywhere and for the absence of the pore texture real eggshell has.

The disclosure standard is simple: the seller states repair, restoration, composite and treatment, and their extent. A buyer who has asked in writing and been answered has a remedy; one who did not ask has a lesson. Stratum records both sides of that exchange.