Some things on beaches obstruct the natural flow of sand, I call them " Flow breakers" objects like boulders, pilings, lifeguard stands, anything that sand is moved around during coastal storms or periods of high surf.
Standing on the beach next to a large rock or iron piling you can often see the lines where the sand has been pushed around the obstruction.
Any coins or jewelry lost at that section of beach you are standing on would have moved with the sand around the sand flow breaking obstacle on the beach.
The larger the sand flow breaker and the busier the beach, the more stuff you can detect around the obstacle that interrupted the natural flow of sand on the beach.
I have always had success searching above large boulders, rocks, pilings etc on the beach and for good reason.
Jewelry, coins and other metal objects wash up and around obstacles but they often get trapped by the obstacle on the way back down the beach.
This makes the upper beach side of sand flow breaking obstacles great places to find stuff after periods of high surf, assuming the high surf made it past the obstacle.
Jewelry and coins tend to be found in a straight-ish line below the obstacle towards the water, after being pulled back down around the obstacle.
The obstacle that diverted the natural flow of sand will dictate how you go about searching the area, I prefer using a small search coil and getting closer to metal obstructions.
Before walking away from any sand flow breaker on the beach I like to do a spiral search pattern around the obstacle to make sure I don't miss anything pushed or deposited away from the obstacle.