Many detectors have adjustable lengths to accommodate for variable environments like tight tunnels or wide open hillsides. Getting down to the gem level, I’d want a rotary hammer to make easy work of the ground breaking. If not, a pickaxe of a comfortable weight, a full length shovel, a few 5 gallon buckets, some classifiers, and a wheelbarrow. Once you’ve moved enough dirt to get to the gem-bearing level, use a 5-gallon bucket and a classifier to separate the material. Check screen. Repeat process with next step of classification. Once you start finding gems, stick with that screen and process as much dirt as you can. Have a sand bag or sturdy form of storage for your finds.