Reading a stone surface

Flint and chert change at the surface over thousands of years. Exposed silica hydrates and leaches, iron and manganese stain, and the surface takes on a rind — white or blue on English and Ohio flints, a cream bloom on many cherts, a gloss on Burlington and Flint Ridge material. Whatever the colour, the rule is the same: a surface that has aged shows the change on every flake scar equally, and a scar that cuts through it is younger than the rind. Look at the piece in raking light with a 10× lens; the new scars are brighter, sharper-edged and a different colour.

Platforms are the second read. An ancient knapper struck with stone or antler and left platforms that are lipped, ground or crushed in ways a modern copper-tipped pressure flaker does not; copper leaves very small, regular, over-steep scars with tiny crushed platforms, especially along the edges. Uniform, perfect serration on a type that is normally irregular is a modern hand. So is a point that is too thin for its size or made of a stone that was not quarried in the type's region.

Resharpening in antiquity and rechipping today both remove edge. The difference is patina and proportion: ancient resharpening left a short blade with an intact, patinated haft, and the scars along the shortened edge carry the same rind; a rechip leaves fresh scars on a blade whose outline is often better than the original ever was. Tip restoration — a new tip flaked on a broken point — shows as a colour change and a scar boundary a few millimetres from the end.

Use-wear and residues are the specialist's confirmation, under a microscope. For the record, photograph both faces and the edges in raking light, note “patina even across all scars” or “fresh scars at tip and left edge”, and set the rechipped flag if it is. The flag prints on the label and the certificate; the trade treats an undisclosed rechip as fraud and a disclosed one as a lesser point.