Diamonds are worn as jewelry and used in a variety of industrial applications. Diamond is the hardest natural substance in the world, and stones that are too small or do not have the requisite quality for jewelry mounting are often used as drill bits or ground into abrasive powder. Others become tools used to cut and polish gem-quality diamonds.
Diamond gemstones are renowned for their luster and sparkle. They are often used in engagement rings and wedding bands. Diamond earrings, necklaces and tennis bracelets are also perennially popular.
Most diamond jewelry features white diamonds. Top quality white diamonds are colorless and have few carbon inclusions. Lower quality white diamonds have a yellow cast. Vibrant yellow diamonds, however, are much rarer and more expensive than the white variety. They belong to the "fancy color' diamond category, which also includes black, pink, green, purple, blue and red stones. Red diamonds are the rarest and most expensive type.
Large diamonds, even those of very poor quality, are exceedingly rare. Consequently, industrial diamond drill bits are not pure diamonds. They are made from a metal, usually iron, with jagged diamond fragments embedded on the cutting faces. These diamond pieces easily slice through tough rocks that are otherwise very difficult to cut.