It is funny that they pulled the hoax in Wyoming, when there really ARE diamonds in Wyoming! There are over 100 known diamond-bearing kimberlite pipes in Wyoming, and another dozen in northern Colorado near the state line. I know, this is outside the southwest area (though Wyoming does have its own desert, the Red Desert) it is a great place to go diamond prospecting and maybe find some!
Read more at
You never know what you will find! Quite a few diamonds were found in CA in the gold rush days, by gold prospectors who found them in their sluiceboxes. (So technically they were placer, as all diamonds found in CA have been so far) Here is what one site says,
http://www.goldmaps.com/ancient_tertiar ... f_gold.htmDiamonds have been found to occur with the gold, mainly at Cherokee Flat in Butte County and in the gravels at Placerville, El Dorado County. The diamonds that have been found were generally of small size and yellowish color. As is the case of diamonds in North Carolina and South Carolina, the diamonds in the California Mother Lode region are mostly scattered.
I don't have my refs handy but one of the other creeks that I recall was Haystack creek,<CA> some decent size (and gem quality) stones were found there. I may be in error on this one, will check and if wrong will post a correction.