People like to look their best at the beach, so it is natural to want to wear jewelry when you hit the sand and the surf. You should think twice before wearing any jewelry to the beach. If you do, remember to take them off before going swimming. If you lose a piece in the ocean, it will probably be impossible to find.
It isn't just the ocean to worry about: You shouldn't wear your jewelry in a swimming pool either. Chlorine can cloud up and tarnish your jewelry over time.
There is a time and a place for luxury jewelry: Exercise and sports is not one of them. Most diamonds and gemstones are sturdy and durable, but that doesn't mean they can't be damaged. Stones can get chipped and cracked if you are engaged in strenuous physical activities. Your gemstones could also scratch and damage other objects and surfaces, which is why wearing jewelry doing anything that involves a lot of handwork is not a good idea.
It is not just your stones you have to worry about. A lot of jewelry have clasps and mountings that can easily be damaged by exercise. You are better off leaving your precious pieces at home before heading out to break a sweat.