We have a collection of over 200 knitting needle gauges, which were collected over a period of about 15 years. We no longer actively collect them. Many are flat and displayed on black velour boards; others are an integral part of a wool holder or needle box so sit on shelves.
The oldest date back to 1847. It is possible to roughly estimate the age of a gauge by looking at the size of needles that it was intended to measure. The oldest gauges are from the days when wool and needles were very fine. Gauges from 1847 have slots for size 28 needles. In those days needles were usually referred to as knitting pins or wires. The sizes were based on the measurement of industrial wires. It may seem contrary that the finest needles had the highest numbers but this is because it relates to how long a piece of wire was stretched out to be. A size 2 needle means that the wire was stretched twice as far as for a size 1 needle. A size 28 means the wire was stretched 28 times as far. 28 needles could be made from the same piece of wire, making a very fine needle.
Naturally, most of our gauges are British though several are from other parts of the world.