Are there diamonds in beach sand?

Yes, there can be diamonds in beach sand, but it is extremely rare and location dependent, so you will not find diamonds on a typical public beach. Diamonds are formed deep in the earth and brought to the surface by volcanic pipes, then eroded by rivers and carried to oceans over millions of years. In a few specific places in the world, diamond-bearing beaches do exist. The most famous are the beaches of Namibia and South Africa along the Atlantic coast, where the Orange River has washed diamonds from inland kimberlite pipes down to the ocean for millions of years, and waves have deposited them in beach sands, which is why Namibia has major beach diamond mining operations. There are also small diamonds occasionally found in beach sands in India, Brazil, and parts of California. However, the concentration is incredibly low, often one diamond per millions of tons of sand, and commercial mining requires heavy equipment. For an average person with a sieve on a normal beach in Florida or California, the chance of finding a natural diamond in sand is essentially zero. What people sometimes find are clear quartz crystals, glass, or zircon that look like diamonds but are not.