Methods and risks

Maintaining a clean diamond can sometimes be difficult, as jewellery settings can obstruct cleaning efforts, and oils, grease, and other hydrophobic materials adhere well to a diamond's surface. Some jewellers provide their customers with sudsy ammonia cleaning kits. Many jewellers use steam cleaners. Some other jewellers sell small ultrasonic cleaners. Home-based cleaning methods include immersing the diamond in ammonia-based or ethyl alcohol-based solutions, or even a solution of mild grease dissolving detergent and warm water. Silver jewellery can be cleaned using aluminium foil, baking soda, and hot water. However, this practice is not recommended by most jewellers.

Certain types of cleaning can damage some jewellery. For example, some class rings are coated with a dark pigment to reduce their shininess. Some gemstones, such as white topaz, have an overlay to produce certain colours. Ultrasonic cleaning can remove this coating, if it is not a quality piece. Ultrasonic cleaning is also contraindicated for opals, pearls and amber, and any other gemstone that is porous. Gemstones that are glued in (a common practice with semiprecious stones in non-precious methods, and in class rings) should not be placed into an ultrasonic cleaner. An ultrasonic cleaner can cause stones that are loose in their settings to come out. Jewellery should always be examined for overlays and loose stones prior to cleaning with an ultrasonic cleaner or a steam cleaner.

Beauty of gems

Although it is not one of the 4 C's, cleanliness affects a diamond's beauty as much as any of the 4 C's (cut, carat, colour, clarity).

A clean diamond is more brilliant and fiery than the same diamond when it is "dirty". Dirt or grease on the top of a diamond reduces its lustre. Water, dirt, or grease on the bottom of a diamond interferes with the diamond's brilliance and fire. Even a thin film absorbs some light that could have been reflected to the person looking at the diamond.

Coloured dye or smudges can affect the perceived colour of a gem. Historically, some jewellers' diamonds were misgraded due to smudges on the girdle, or dye on the culet. Current practice is to thoroughly clean a gem before grading its colour as well as clarity.

Cleanliness does not affect the jewellery's market value, as jewellers routinely clean jewellery before offering it for sale. However, cleanliness might reflect the jewellery's sentimental value: some jewellers have noted a correlation between ring cleanliness and marriage quality.

Diamond is an allotrope of carbon. It is the hardest known natural material and the third hardest known material after aggregated diamond nanorods and ultrahard fullerite. Its hardness and high dispersion of light make it useful for industrial applications and jewelry.

Diamonds are specifically renowned as a material with superlative physical qualities; they make excellent abrasives because they can be scratched only by other diamonds, Borazon, ultrahard fullerite, or aggregated diamond nanorods, which also means they hold a polish extremely well and retain their lustre. Approximately 130 million carats (26,000 kg) are mined annually, with a total value of nearly USD $9 billion, and about 100,000 kg (220,000 lb) are synthesized annually.

The name diamond derives from the ancient Greek adamas They have been treasured as gemstones since their use as religious icons in ancient India and usage in engraving tools also dates to early human history.Popularity of diamonds has risen since the 19th century because of increased supply, improved cutting and polishing techniques, growth in the world economy, and innovative and successful advertising campaigns. They are commonly judged by the four Cs: carat, clarity, color, and cut.

Roughly 49% of diamonds originate from central and southern Africa, although significant sources of the mineral have been discovered in Canada, India, Russia, Brazil, and Australia. They are mined from kimberlite and lamproite volcanic pipes, which brought to the surface the diamond crystals from deep in the Earth where the high pressure and temperature enables the formation of the crystals. The mining and distribution of natural diamonds are subjects of frequent controversy such as with concerns over the sale of conflict diamonds (aka blood diamonds) by African paramilitary groups.