Helical Compression Spring

Yes if you look in the catalogue of the company Gutekunst (Germany) A spring manufacturer, you find at every spring description the diameter of a gauge for external and an other for internal limits. Tolerances are according DIN.

I'll begin by saying that I work for a spring manufacturer in the US who makes hot and cold wound springs.

It really depends on the customer and the tolerance required when determining how to inspect the part. For standard tolerance springs, we generally check the OD with calipers on the end coil. For certain applications we also check to make sure it fits in a tube or over a rod of a certain length and diameter. If you want to specify a ring gauge, it is acceptable, but you should either provide the gauge or be explicit in specifying the diameter and length of the gauge.

Also be aware that cold coiled springs are much more accurate in the OD than hot coiled spring. Hot coiled springs are usually made on a tapered mandrel to allow them to pull off and they see changes in their OD during heat treat.

I hope this information helps.