It would be best if you can find out strand size and then number of each and you can compare area, which is what determines what gauge a wire is. Diameter can be deceiving just because very larger strands will have more air gaps and thus have a larger diameter. The smaller strands will be more tightly packed together.
For the most part Stinger and other reputable companies will devulge that information freely - others you need to research like you are. The welding supply stuff uses 30 gauge strands w/ neoprene jacket where most audio cables use 36 gauge strands and PVC. Neoprene is not as weather/oil resistant as PVC and the coper is not OFC. One reason our Kolossus Kable is tinned - it makes it marine grade and will never oxidize.
Oh and the KLM and KOL 1/0 are ~ 7/16"