We have camped there a few times. The campground is nice and has a few trails to hike. The "mine", it self is a big open plowed field that you just pick a spot and dig. The staff will help you identify what you find. They say the best time to dig is after it rains. There is a charge for admission. You can bring your own shovels, buckets and screens, or rent them there. You will need sun screen and a hat or some type of shade to keep the sun off.
Here is a link to the park:
http://www.craterofdiamondsstatepark...-for-diamonds/