Approximate Diameter (≈) / Equivalent Gauge (=)
Gamut gut string gauges are approximate (≈) diameter. Meaning, that while a ≈0.60mm string is polished in the workshop to a diameter of 0.60mm, changes in ambient humidity, temperature, shipping, and storage can cause the natural gut string to expand or contract slightly.
Gimped gut strings and gut/metal-wound equal tension strings are gauged with the equivalent-gauge (=) system. This means that the gauge listed, such as =1.50mm, indicates that the string is approximately equal in weight to a plain gut string of that diameter. Of course, because the wire is much heavier than gut, the string will be much thinner than a plain gut string of the same weight.
