The definitions

A figure that admits it is approximate

On this page11

Every other threshold described across these properties is stated exactly And several of them go further and resolve the boundary The seed pearl definition goes the other way Which is the right choice for what it measures So the alternative would have been a false precision This library has one rule that solved the same problem differently Two answers to the problem of measuring an irregular thing And the cashmere definition is a third answer Three rules, three strategies, one underlying problem And none of them is in play on this shelf References

Approximately two millimeters or less. The only one in this library.

Every other threshold described across these properties is stated exactly

Nine thousandths of one percent of a dried paint film. Three and a half seconds of flame spread. Nineteen microns of average fiber diameter. Five hundred milliliters of container capacity. Fifteen percent of surface area.

And several of them go further and resolve the boundary

The flammability standard writes out in a table that 3.5 seconds is a pass. The intermediate flammability class says four through seven seconds, both inclusive. Those rules work hard to remove ambiguity at the edge.

The seed pearl definition goes the other way

Approximately two millimeters or less. It declines to specify the boundary and says so in one word.

Which is the right choice for what it measures

A pearl is irregular. It has no single diameter, its dimensions differ in every axis, and a figure to the tenth of a millimeter would be describing a measurement nobody could reproduce.

So the alternative would have been a false precision

Stating 2.0 millimeters exactly would imply a measuring method and a measuring axis that the definition does not provide. Approximately is a statement about the limits of the measurement, not a weakness in the rule.

This library has one rule that solved the same problem differently

The small parts regulation defines a hazard by whether an object fits a named cylinder, in any orientation, which settles every axis of an irregular object at once without stating a dimension at all.

Two answers to the problem of measuring an irregular thing

Say approximately and accept the imprecision, or build a gauge and make the apparatus the standard. Both are better than a precise number that cannot be applied.

And the cashmere definition is a third answer

An average diameter, a tail condition on the coarse end, and a coefficient of variation. Which handles irregularity by describing the whole distribution rather than by picking one number from it.

Three rules, three strategies, one underlying problem

Approximately, a gauge, or a distribution. Which of the three a rule uses says a great deal about what it is measuring and how it expects to be enforced.

And none of them is in play on this shelf

Nothing here measures a stone. The containers section measures the one property of a container that bears on a group judged by eye, which is whether light gets through it.

References

16 CFR 23.19, Definitions of various pearls. "(a) Pearl: A calcareous concretion consisting essentially of alternating concentric layers of carbonate of lime and organic material formed within the body of certain mollusks, the result of an abnormal secretory process caused by an irritation of the mantle of the mollusk following the intrusion of some foreign body inside the shell of the mollusk, or due to some abnormal physiological condition in the mollusk, neither of which has in any way been caused or induced by humans. (b) Cultured pearl: The composite product created when a nucleus (usually a sphere of calcareous mollusk shell) planted by humans inside the shell or in the mantle of a mollusk is coated with nacre by the mollusk. (c) Imitation pearl: A manufactured product composed of any material or materials that simulate in appearance a pearl or cultured pearl. (d) Seed pearl: A small pearl, as defined in paragraph (a), that measures approximately two millimeters or less." And 16 CFR 23.22, which makes it unfair or deceptive to misrepresent "the manner in which cultured pearls are produced, the size of the nucleus artificially inserted in the mollusk ..., the length of time that such products remained in the mollusk, the thickness of the nacre coating" or the value and quality of cultured pearls compared with pearls and imitation pearls. law.cornell.edu

The Davis Pack Supply catalog, measured 19 October 2026. Of the 184 containers on this shelf, 76 are recorded as clear and 4 as frosted, so 80 pass light in some form. 32 are amber and 2 dark amber, which is 34 that block it. The remaining 70 are 24 white, 18 black, 16 blue, 9 green and 3 natural. By material the shelf is 119 PET, 41 glass and 24 polypropylene. Cross-tabulated, 54 of the light-passing rows are clear PET, 21 are clear glass and 3 are frosted glass. No row on this shelf is recorded as clear polypropylene; the closest are the 3 recorded as natural, which is unpigmented polypropylene and translucent rather than clear. The record states a color name and not an optical property, and clear, frosted and natural denote three different optical states that the record does not grade.

Written from 16 CFR part 23 and from the catalog as it stood on 19 October 2026. Part 23 contains the Federal Trade Commission guides for the jewelry, precious metals and pewter industries and addresses how a seller may describe a stone or a pearl; it does not govern containers, and it does not reach any row on this shelf. Nothing here states the identity, origin, grade, value or treatment of any stone, and nothing here is grading, appraisal or authentication guidance. The catalog records a container color, not an optical performance, and no page converts one into the other.