What is open#

Touchstone publishes the arithmetic that turns a card condition assessment into a grade. It does not publish, and does not specify, how you arrive at the assessment in the first place. That line is worth stating plainly, because a standard that is vague about its own edges is asking to be trusted rather than checked.

What the standard covers#

Everything needed to compute a grade, and to prove you computed it correctly:

• The normative specification — the rubric, which is the authority. Where the prose and the reference implementation disagree, the prose governs and the disagreement is a bug in one of them, filed and fixed.
• The rubric data — every penalty as a number you can read, not a constant compiled into something.
• The reference implementation — one dependency-free module. It is conformance evidence, not the definition.
• The schemas — the shape of an assessment going in and a result coming out.
• The conformance vectors — frozen inputs paired with the exact output every implementation has to reproduce.

All of it under Apache-2.0. See the licence for what that commits us to, and for the part that cannot be narrowed.

What the standard does not cover#

How the assessment is produced. Touchstone takes centering measurements and an enumerated list of defects as its input. Where those come from is out of scope: a person with a loupe and a ruler, a scanner, a vendor's software, or a machine-learning model are all equally valid sources, and the standard takes no position on which. Two implementations that disagree about whether a corner is minor or moderate will produce different grades, and Touchstone cannot help with that — it guarantees only that they will agree once they agree on the input.

This is a real limit, not a modest one. It is also where the honest claim lives: given the same enumeration, any implementation produces the same number. You do not have to take that on faith. Run the vectors.

The steward's own perception model is closed#

Grailology, which stewards Touchstone, sells grading. The part of its product that turns an image into an assessment — measuring centering, finding and classifying defects — is proprietary and stays that way.

We would rather say that than imply otherwise. The claim we can defend is not that there is no closed component anywhere; it is that the closed component never decides the grade. Once the assessment exists, the arithmetic is public, and anyone can recompute the result and disagree with it in specific terms — this row, this penalty, this rule.

An assessment you disagree with is a disagreement about a card. A grade you cannot recompute is a disagreement you are not allowed to have.

Who needs an account#

No account, ever. The specification, the schemas, the conformance vectors, the reference implementation, and the hosted reference scorer. All of it usable, and self-hostable, by someone with no relationship to Grailology whatsoever. This tier is what makes charging for the others legitimate.

Hosted and metered. Grailology operates a hosted Touchstone MCP server for use inside AI tools. Hosting costs money and has to be rate limited, so it is account-gated.

The Touchstone MCP server is provided by Grailology, which uses Touchstone as its grading standard. It is not operated by the Touchstone project.

Commercial. Grailology's own grading, attestation and registry services. These are products built on the standard; they are not the standard, and nothing about them is required to use it.