What does GG stand for in weight?

Excuse me, but could you clarify for me what the abbreviation "GG" stands for when it's used in the context of weight? I've come across it a few times but haven't been able to pin down a definitive explanation. Could it be a metric or imperial unit of measurement that I'm not familiar with? Or perhaps it's shorthand for a specific type of weight, like a gram or a kilogram? I'd really appreciate it if you could shed some light on this for me.