TTO 0056 Coral & Pearl String Beautiful Coral and Pearl necklace. Generous in length at around 43 inches this is a piece of pure luxury. The pearls are around 3/16" in diameter. The value of the pearls in jewellery is determined by a combination of the luster, color, size, lack of surface flaw and symmetry that are appropriate for the type of pearl under consideration. Among those attributes, luster is the most important differentiator of pearl quality according to jewelers. Coral's many colors give it appeal for necklaces and other jewellery. Intensely red coral is prized as a gemstone. Precious coral or red coral is the common name given to Corallium rubrum and several related species of marine coral. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink skeleton, which is used for making jewellery.