Pearl (with Peridot)

Pearl: Hardness 2.5–4.5, White/Cream color, Pearly luster, Amorphous/Orthorhombic structure, No cleavage, SG 2.60–2.85. Peridot: Hardness 6.5–7.0, Olive green color, Vitreous luster, Orthorhombic structure, Poor cleavage, SG 3.2–4.3.

Pearls are organic gems formed inside the soft tissue of living shelled mollusks. Peridot is an igneous mineral formed deep within the Earth's mantle and brought to the surface by volcanic activity; it is one of the oldest known gemstones, dated back to ancient Egypt.

Primary use is in fine jewelry (necklaces, bracelets, earrings) and high-end fashion accessories. Cultured pearls are a major global industry, while peridot is of interest to collectors and used as the August birthstone.

Pearls are the only gemstones made by living animals. Peridot is unique because it is one of the few gemstones that occurs in only one color: olive-green. Peridot has also been found in pallasite meteorites, meaning it exists in outer space.

Identify pearls by the 'tooth test' (feeling gritty against teeth) and their distinctive orient/luster. Identify peridot in the field by its distinct bottle-green color, lack of acid reaction, and occurrence in basaltic rocks. Major locations for pearls include Japan, China, and Australia; for peridot, notable sources include Myanmar, Pakistan, and Arizona.