Nuggets are easy, but the fine to very fine gold that makes up the bulk of the gold found placer mining is much harder. Heavy black sands increase the difficulty and time involved. The Blue Bowl speeds it up again.
Water is pumped into the bowl and drains through a tower in the center. Lighter material spirals around the Blue Bowl, up the side of the tower and out the hole in the middle. Heavier gold sits on the bottom or at the base of the tower.
The two main keys to success with the Blue Bowl is to classify your material down as fine as you can go (at least 30 mesh), and to level the bowl prior to use. Use the valve to adjust the speed of flow. The finer the material is screened to, the slower the water needs to be and the finer the gold you'll capture.
We carry many sizes of classifiers to help with pre-screening.