One of my favorite pastimes in the Cape May area as a child was to go to Sunset Beach at "The Sunken Ship" and collect Cape May Diamonds.
Although some things have changed, the Cape May Diamonds are still available in abundance right on the shoreline. They are small quartz crystals which seem to wash up on one part of the beach in Lower Township near Cape May Point. This area is located near the mouth of the Delaware Bay where it meets the Atlantic Ocean.
These diamonds are usually cloudy or slightly transparent when found on the beach. However, they can become crystal clear after a few weeks in a gem tumbler. They still have no real value, at least in monetary terms. You can see many people collecting these stones any time you visit. The polished versions are available at a gift shop located on site.
Go check it out next time you are in the area.