Vintage Sterling 925 Crushed Coral and Brass Abstract Slab Earrings Vintage Coral Slab Earrings. Vintage Sterling Aztec Crushed Coral Earrings. I am not sure what kind of stone makes up the main base portion of the earring. Possibly crushed gray coral. But the inlays are crushed coral pebble pieces. The posts do acid test as sterling. This has been coated over and there is some markings on one of the edges as shown in photos. Measurements Length: 1 5/8 inches Width: 3/4 - 1 1/8 inches