Authentic sea glass has unique physical characteristics that "craft glass" or machine-tumbled glass cannot easily replicate. The most definitive sign of real sea glass is the presence of "C-shaped" pores and a frosted, pitted texture caused by years of chemical "hydration" in salt water. Under a magnifying glass, real sea glass will show tiny, crescent-shaped abrasions that are uneven and random. In contrast, fake sea glass is often chemically etched or tumbled with uniform grit, resulting in a satiny, smooth surface that lacks these microscopic pits. Real sea glass also tends to have rounded, "frosted" edges that feel smooth but not "slippery," and it may still retain embossed lettering or features from its original life as a bottle or jar. A grounded "reality check" for 2026: if you find a large quantity of rare colors (like bright red, orange, or cobalt blue) that all have the same thickness and shape, it is almost certainly man-made "craft glass" rather than a natural ocean find.