United States (numeric)
JewelryWiki Editorial·1 source·Reviewed 2026-08-04
A numeric scale of 1 to 13 with quarter sizes, descended from an 1874 patent that describes the gauge but never states its dimensions. In 1921 the US Bureau of Standards reported that no published dimensions existed — and this site has found no later standard that fixed that.
Properties
| Property | Value | Authority |
|---|---|---|
| How a size is written | A number, on gauges graduated 1 to 13 or 0 to 13 with quarter sizes. The Bureau of Standards found gauges almost universally of the cone type under two trade names, “F. E. Allen’s” and “U. S. Standard”, apparently working on the same principle and differing only in the shape of the wooden handle. The earliest known patent for the conical ring gauge is F. E. Allen’s, 3 February 1874, US Patent No. 146974, which describes the gauge and its auxiliary circumference scale accurately — but, in the Bureau’s words, “the dimensions of the sizes are not stated”. [1] | — |
| Standard status | No published dimensional standard, stated as such by the national standards body. The Bureau wrote: “All attempts to find any printed statement as to what the dimensions of the various sizes are supposed to be, have been unsuccessful,” and concluded that “while there apparently is only one standard in use in the United States, in reality, because of the lack of specific dimensions and because of the errors introduced by the adoption of a common commercial article as a pattern, there are many, although similar, standards.” A manufacturer wrote to the Bureau in 1917 that “our standard was probably obtained from a commercial Allen ring gage and there appears to be considerable variations in the ring gages on the market.” [1] | — |
| Defining body | None. The Bureau of Standards stated in 1921 that it intended to take the problem up and select values best representing the average of existing standards; this site has not found a resulting published standard. [1] | — |
| Where the ring is measured | Not fixed, and the Bureau treated this as a distinct problem in its own right: “Some companies bring the top of the ring to the mark on the gage, others use the middle of the ring, while still others use the lower edge of the ring. These differences in the method of use are equivalent for broad rings to an appreciable part of a size, and serve to increase the differences between the various standards.” This is precisely the ambiguity ISO 8653:2016 removes by specifying the measurement point per inside profile. [1] | — |
| What to watch for | The Bureau quantified the spread it found. Two gauge manufacturers gave the diameters of sizes 1 and 13 as 0,485 and 0,877 inch, and 0,491 and 0,877 inch. Gauges measured in retail houses in a single locality in one afternoon ranged from 0,480 to 0,491 inch at size 1 and 0,870 to 0,878 inch at size 13, and gauges in a few shops in one city differed by about a third of a size — with the Bureau noting that searching other cities “may be expected to disclose much larger differences”. It also records a buyer who received platinum ring blanks that measured about a quarter size smaller than ordered, with “no means of recourse”. [1] | — |
Sources
- Circular of the Bureau of Standards No. 43 (2nd ed.) — Jewelers’ and Silversmiths’ Weights and Measures — United States Department of Commerce, Bureau of Standards (NBS Circular 43, 2nd ed., 24 January 1921, section VII "Ring sizes", pp. 39–40)