The brilliance of a diamond results from its properties of refraction, reflection, and dispersion. Upon passing through a diamond aspect (one of the many little planes cut onto the gem surface), a lightweight ray is refracted, or bent. The bent ray is mirrored from a bottom facet upward through a top facet. In refraction every color of the ray is bent at a rather totally different angle. This spreading of colors is termed dispersion. Since refraction occurs each as the ray enters and because it leaves the diamond, dispersion conjointly happens twice. So the ray is emitted as a glittering rainbow. Of all gems the diamond has the highest index, of refraction: 2.419.

Most diamonds are tinged with color. If a diamond's color is sufficiently intense, it's prized as a gem and called a “fancy.” Blue and pink diamonds are the most valuable. Red diamonds are very rare. Clear white diamonds are referred to as diamonds of the primary water.

When found or mined, diamonds seem like fragments of glass. 2 or more gems are sometimes cut from a rough stone. Diamonds are initial split or sawed along the grain of the stone. The pieces are then mounted during a lathe. The fast-turning gem is shaped roughly by a diamond-tipped tool. The stone is then placed in solder in an exceedingly dop (holder), and a facet is ground on the surface by a spinning iron disk bearing a paste made of diamond mud and olive oil. The cutting of each facet requires changing the position of the stone in the dop. So as to understand the larger diamonds, dops are equipped with mechanical holding fingers.

Diamond gems have been cut in many completely different shapes. The brilliant cut is the most popular. This has fifty eight facets, 33 above the girdle (circle at greatest diameter) and 25 below. The diamond cutter is very skilled. His task is to place the aspects so that the foremost light rays will mirror through the top facets. Antwerp, Tel Aviv, India, and New York Town are the biggest centers of the fashionable diamond-cutting industry. Amsterdam is a historic cutting center.

In even the best gem-manufacturing areas solely concerning 25 per cent of the diamonds mined are of gem quality. The remainder, of poor gem quality because of color or faults, are utilized in industry. An previous saying, “it takes a diamond to chop a diamond,” is true. Diamonds are used by the lapidary (gem cutter) to form and polish diamonds and alternative gems.

The stones also are used to true the surfaces of precision grinding wheels. In machine outlets tools tipped with diamonds cut grooves around automobile pistons and perform alternative precision cutting tasks. Needles tipped with diamond dust drill holes through some diamonds. This could be done electrically. Diamonds with holes are used as feeder nozzles for oil furnaces and as wire-drawing dies. Some 400 tons of copper will be drawn through a diamond die into a wire fine enough to circle the globe 20 times before the die shows signs of wear. Geologists and engineers use diamond-tipped hollow steel bits for drilling into the world to secure samples of deep-lying rock formations.