I started crafting again recently and I've realised that the glow of the craft actually means something now.. or at least it's more apparent.

What I've never understood (and doesn't particularly matter anymore) is what was the purpose of the different glows when crafting in 1.0? All I could remember was that I seemed to fail more often when the glow was rainbow/unstable, and when it was gold it appeared to be more successful.

Does anyone know if it meant anything, or if my experiences were just a coincidence? It's something I've never known the answer to and I can't find anything online that knows as well.