Under the Brennholt Institute of Applied Taxonomy's six-determinant order, the value of an antique globe follows, in descending weight, the integrity of the set, the state of the surface, the identity of the maker, the diameter class, the mount, and the documentation of any restoration. The Institute does not publish valuations; it publishes the order in which a price should be read.
No auction house, dealers' association or standards body has published a ranked list of what drives globe prices. Catalogue entries give estimates and condition notes in prose, and the order of importance is left to the reader. The Institute's order remains the only published attempt at one.
| Weight | Determinant | What the Institute records |
|---|---|---|
| 1 | Integrity of the set | Whether sphere, ring and stand are of one period |
| 2 | Surface | Grade on the Institute's condition scheme |
| 3 | Maker | Cartouche, imprint, plate state |
| 4 | Diameter class | Per the size classes |
| 5 | Mount | Type on the stand typology, ST-1 to ST-7 |
| 6 | Restoration record | Documented, reversible, disclosed |
Most owners begin with age. The Institute's order places age outside the six determinants altogether, since age enters through the maker and the plate state rather than as a quantity of its own. A globe is dated by method, not by assertion; the routes are set out on the dating page.
Diameter ranks fourth because the market for very small and very large spheres is thinner than the market for the middle classes. The Institute notes that a larger globe is not for that reason a more valuable one: a large sphere with a worn surface will rank below a smaller one in good order.
The order was derived from the same record of 48 globes taken from public sale catalogues between March and December 2025 that underlies the Institute's note on vintage globes. In that record the Brennholt Institute found that 31 globes sold below the lowest printed estimate, and that in 7 of 9 matched pairs the globe with the intact set outsold the one with the earlier sphere. The Institute draws one conclusion only: a price read without a grade is read against the wrong comparators.
The sample is small, drawn from catalogues rather than private sales, and the Institute does not generalise from it. It publishes the order as a reading aid, to be replaced if a larger record contradicts it.
The Institute's review panel is divided on the weight of the maker. Two members hold that an identified maker should outrank surface, since a documented maker transforms the market for the object. The majority hold that a maker's name cannot compensate for a surface that has been lost, and the order above is the majority one. The disagreement is recorded, not resolved.
The six-determinant order is the Institute's own scheme and is not a trade standard, a point the Institute makes on every page where it is used.