it is the weathering, tumbling, and aging in sand and saltwater that gives real sea glass, its unique "frosted" appearance, and "soft" texture. A process called "hydration" is responsible for the pitting. As the glass soaks in the sea water, the lime and soda used in making the glass leaches out and leaves little pits on the surface. Sometimes the soda and lime also mix with other minerals, forming sparkling crystals on the surface of the glass. Hydration, or pitting, does not occur in fresh water because the PH of the fresh water is wrong. Technically, fresh water glass is called "beach glass", while salt water glass is called "sea glass".