Gem name: diamond jewellery

It's easy to see why diamond jewellery is a woman's best friend!

Diamond jewellery is unquestionably the most coveted and popular form of jewellery in the world. Couples throughout the world become engaged through the gift of a diamond ring, and these breathtaking stones are staples in the most magnificent gem collections on Earth. Diamonds (except the black variety) are formed through intense heat and pressure between 50 and 250 miles beneath the surface of the planet. Over millions of years, the stones travel upward towards the surface. All diamonds in existence today are over one billion years old. Geologists believe that black diamonds are also billions of years old. However, these diamonds are not created on Earth, but were probably deposited in the planet's crust during an ancient collision with a sizable asteroid. Black diamonds have only been mined in Brazil and the Central African Republic. All other colors of diamond are abundant in India, Russia, Australia and many parts of southern and central Africa.

Diamonds are fascinating gems with brilliant sparkle and extreme hardness. Gemologists measure the hardness of gemstones using the Mohs Mineral Hardness Scale, which runs from 1 (extremely soft) to 10 (extremely hard). Diamond has a ranking of 10 on the Mohs scale and is the hardest substance known to humankind. Diamond's hardness makes it an extremely useful industrial material; specimens that aren't suitable for use in jewelry are important components in polishing equipment, scalpel blades, and abrasive powders. Diamond cutting tools are essential in the gem trade because diamond is the only material that can cut other diamonds.

The most widespread and popular type of diamond jewellery is the diamond engagement ring. These rings are usually worn every day and are often subjected to a great deal of wear and tear. Diamond's extreme hardness makes it resilient to chipping, scratching and splitting, and helps each stone maintain its brilliant sparkle without much maintenance. The diamonds used in engagement rings are usually clear and retail for over seven thousand dollars per carat, although the price depends heavily on the clarity and color of the stone. Clear, perfectly colorless diamonds are the most prized. Diamonds may also be brightly colored. These "fancy diamonds" are much more expensive than their clear counterparts. Canary yellow diamonds are the most popular type of fancy diamond; blue and black are also popular, but are rarer than the yellow variety and much more expensive. The rarest type of diamond, the red diamond, sells for over one million dollars per carat.

Thousands of jewellery designers use diamonds in their work. Tiny, inexpensive stones adorn the shanks of rings and are popular in luxury wristwatches. Mid-size diamonds with good clarity make beautiful earrings and tennis bracelets. Larger specimens are often used as center stones in rings and necklaces. Diamond engagement rings are available from almost every jewellery store in existence, including major chains such as Zales and department stores of all sizes. Diamonds are also readily available in Manhattan's "diamond district," a New York neighborhood that is home to hundreds of independent gem vendors and jewellery boutiques.