I know you want to find a diamond, as do we all, so I'd like to offer some information that will help you. The following is information taken for the website for the Crater of Diamonds Park in Arkansas.
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This is a picture of diamonds found at the park. Note their size relative to a human hand, their color, their crystal structure, and the surface texture (or lack thereof).
Other information from the park's website says "More than 33,100 diamonds have been found by park visitors since the Crater of Diamonds became an Arkansas state park in 1972. Notable diamonds found at the Crater include the 40.23-carat Uncle Sam, the largest diamond ever unearthed in the U.S.; the 16.37-carat Amarillo Starlight; the 15.33-carat Star of Arkansas; and the 8.52-carat Esperanza."
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For comparison, 1 carat of diamond weighs 0.2 grams (two-tenths of a gram). That means the largest diamond found at the Crater of Diamonds weighed only 8.046 grams ... far less than a pound (453.592 grams).
Do your research. Find the right places to search. Keep at it. You may be rewarded with a raw diamond if you look in the right places. Remember, diamonds don't just happen in random places. The conditions have to be right for their formation.
Good luck.