also... The diamond mine is in Murfesboro (sp.). I think it's about 45 minutes or so from HS. Call it an hour since you don't know the area.
Tip: The diamonds are in the gravely soils below the plowed surface soils. You can still find them on the surface, but the only ones who do are those who have hunted a lot and have developed an eye for what they look like. Dig down a ways until you hit the fine gravel. Take a sample and head to the wash station to carefully comb though it. Anything that looks smooth and translucent, put to the side and take it to one of the park guys and they will let you know what you've got.
Last month some kid found a 5 carrot brown diamond. Tiny ones are common.