From Gold Coast Treasure Hunters “This chart shows the VDI (sometimes called TID, for Target ID) numbers for over 50 gold rings, which Bill pushed into a thick cardboard sheet. White’s VDIs are down the left, Minelab down the right. Weight in grams is across the bottom. Notice the nickel’s position in the center of the chart.” Bill Watson's Gold Ring VDI Chart The photo almost perfectly illustrates a study Fisher did decades ago on the distribution of rings and target ID. There ar