Pound (mass) a legal unit for trade (it was abolished in the United Kingdom on 6 January 1879 by the Weights and Measures Act of 1878), but the troy ounce, of a troy pound, is still used for measurements of gems such as opals, and precious metals such as silver, platinum and particularly gold. The system called Tower weight was the more general name for King Offa's pound. This dates to 757 AD and was based on the silver penny. This in turn was struck over Arabic dirhams (2d). The pound was based on the weight of 120 Arabic silver dirhams, which
Precious coral Precious coral Precious coral, or red coral, is the common name given to a genus of marine corals, Corallium. The distinguishing characteristic of precious corals is their durable and intensely colored red or pink-orange skeleton, which is used for making jewelery. Red corals grow on rocky seabottom with low sedimentation, typically in dark environments—either in the depths or in dark caverns or crevices. The original species, "C. rubrum" (formerly "Gorgonia nobilis"), is found mainly in the Mediterranean Sea. It grows at depths from 10 to 300 meters below sea level, although the shallower of these habitats have been largely depleted