Jewellery stones and tools

Jewellery stones decorate items; their value depends on colour, hardness, purity, size and brilliance. A mineral is a solid substance of a certain composition formed naturally in nature. Jewellery stones are usually divided into five groups: precious (diamond, ruby, sapphire, emerald, pearl), coloured (turquoise, malachite, nephrite, agate, chalcedony), organic (amber, coral, jet), various coloured ornamental stones and synthetic stones. Diamond is crystalline carbon, one of the hardest natural substances; ruby and sapphire are the red and blue varieties of one mineral, corundum. Turquoise is a bluish-green, brittle, opaque stone whose colour can change with time; a pearl forms inside a shell, and amber is tree resin hardened into stone. Stones are cut as a smooth dome (cabochon), stepped, or many-faceted (brilliant). The jeweller uses a punch (punson), a draw plate (kurya) for pulling wire through holes, dividers (pargor), a chisel (zubilo), a small hammer, tongs, pliers, shears and moulds; heating and casting are done only by a master or under the teacher’s supervision.