I would say your 2 sieves, a pair of cloth/rubber coated gloves, small folding shovel and miners pick, a pocket led torch, tweezers and a bumbag or small container to put your rocks in and some drinking water and good walking shoes are the essentials. I also wear neoprene waders so I can walk across water ways without leach issues.
Everything else is up to you. Tweezers a must in my opinion to help sort through and the led light for those black looking stones that are really blue under good light.
When gem hunting a known location, unless you have nailed a particular spot, walking around and test sieving every few metres will guarantee you some pretty stones.
Essentially minimal gear allows for much more freedom to explore and not get tired carrying stuff! Keep the big guns (crow bar/mattock/shovels/buckets etc) in the car if required. I can keep all the above essentials in a little backpack with my lunch, often if you have gloves you don't even need the shovel- just on the hands and knees and scoop with your hands- ive spotted a 7 carat by eye before it made it to the sieve.