Now that you know the answer is 7.78g are you going to invest in an accurate scale or a cheap and nasty one? The law specifies the hallmarking threshold to an accuracy of 2 decimal places. Many of the cheaper scales don’t have a resolution of 0.01g which is what you need.

These are the scales I bought:Kern-Precision-Balance-Pfb-600-2M-PFB-600-2M