A specification clause becomes enforceable when three elements are present: the parameter is measurable, the tolerance is numeric, and the reference document is named. "Colour to match sample" fails on all three; "colour ΔE ≤ 2.0 against control sample #A-2026-04, held by supplier" holds on all three.
The parameters that carry the most weight in commercial disputes are dimensional tolerance, colour tolerance, moisture content at dispatch, warranty term and inclusion / exclusion of installation. Each should be stated numerically against a named reference.
What to avoid
Adjectival specifications — "premium quality", "consistent finish", "matching batch" — do not survive scrutiny. They cannot be measured, so they cannot be enforced. Where a project team wants these qualities, they should be converted into numeric tolerances at specification stage, not at delivery stage.