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Roger Weller, geology instructor                     

Michael Schweska
Physical Geology
Spring 2005


                                         April Birthstone-Diamond

Diamond is the official birthstone for April as adopted by the American National Association of Jewelers in 1912. Diamond is suggested as a gem to give on the 10th and 60th wedding anniversaries. Diamond is a perfect "10" on the Mohs scale of hardness. Diamonds were discovered in India in 500 B.C. and since ancient Greece, Diamonds have been the traditional symbol of love, and the ancients believed they were hardened dew drops, splinters from the stars or crystallized lightning. Gem-quality diamonds are mined around the world, but the largest producers are South Africa and its neighbors. Russia, Australia and Brazil are also major producers. Diamonds come from the mines in crystals, often with eight sides. As much as 60 percent of the original crystal is cut away to create a round brilliant diamond. A Diamond is the hardest substance known to humankind, and is made of a crystallized carbon that has unique powers of light reflection. Since diamonds are composed of a single element, they are the purest of all gemstones. Diamonds Click here for a picture in natural form. Click here for more faceted and natural specimens.


Diamonds may be nearly any color in the rainbow plus browns, grays, and white. Shades of yellow are most common, followed by colorless. Blue, black, reddish, and greenish are more valuable (some extremely so). Diamond is the ultimate gemstone, having few weaknesses and many strengths. It is well known that Diamond is the hardest substance found in nature, but few people realize that Diamond is four times harder than the next hardest natural mineral, corundum (sapphire and ruby). But even as hard as it is, it is not impervious. Diamond has four directions of cleavage, meaning that if it receives a sharp blow in one of these directions it will cleave, or split. A skilled diamond setter and/or jeweler will prevent any of these directions from being in a position to be struck while mounted in a jewelry piece. As a gemstone, Diamond's single flaw (perfect cleavage) is far outdistanced by the sum of its positive qualities: broad color range variable, high refraction, high dispersion or fire, very low reactivity to chemicals, rarity, and of course, extreme hardness and durability. The name Diamond comes from the Greek word "Adamas" which means "unconquerable" - suggesting the eternity of love.


The formula for Diamond is C, Elemental Carbon. Diamond is a polymorph of the element carbon. Graphite is another polymorph. The two share the same chemistry, carbon, but have very different structures and properties. Diamond is hard, Graphite is soft (the "lead" of a pencil). Diamond is an excellent electrical insulator, Graphite is a good conductor of electricity. Diamond is the ultimate abrasive, Graphite is a very good lubricant. Diamond is transparent, Graphite is opaque. Diamond crystallizes in the isometric system and graphite crystallizes in the hexagonal system. Somewhat of a surprise is that at surface temperatures and pressures, Graphite is the stable form of carbon. In fact, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow.

The Value of a Diamond: The Four C's

Shape (Cut)

The Cut is the factor that determines the brilliance of a diamond. A classic round brilliant cut diamond has 58 facets: 33 on the top, 24 on the bottom, and the culet (1 point at the bottom). Each of the diamond's facets must be placed in exact geometric relation to one another when the stone is being cut. Quality diamonds must be properly cut and not "spread", which means that the proper proportions are compromised to make the diamond weigh more. Coomon cuts include: Round, Oval, Pear, Marquise, Heart, Emerald, Princess and Radiant.


The Clarity of a diamond is based on the number, location, size, and type of inclusions found in the stone. An inclusion is an imperfection or trace mineral in the stone that is visible under the magnification of a jeweler's loupe. The fewer inclusions the diamond has; the clearer, more brilliant and more expensive the diamond will be. A "Flawless" diamond is one that has no inclusions and is extremely rare and valuable.


Colorless and near-colorless diamonds are the most valuable. Though most diamonds may appear colorless to the naked eye, the majority of diamonds contain slight traces of yellow or light brown when viewed under a jeweler's loupe. Depending on the stone's size, a single increase in color grade can boost the value of a diamond by thousands of dollars per carat. A traditional engagement diamond is usually colorless or near-colorless.
In nature, diamonds can also occur in shades of red, pink, blue, green and deep yellow - These are called "Fancy Diamonds". In the United States and around the world colorless diamonds are graded on an alphabetical scale, introduced by the Gemological Institute of America (GIA). "Colorless" or "rare white" diamonds are of color grades D, E and F. Diamonds of color grade D are very rare, and extremely valuable.


The weight of a diamond is measured in carats. But, the carat weight alone is almost meaningless unless you also consider the cut, clarity and color of the diamond. A large diamond is not very valuable if it lacks brilliance, purity and high-grade color. However, since larger stones are rarer than smaller ones, diamond value rises exponentially with carat weight. Therefore, a diamond weighing 3.0 carats, will always be worth more than three 1.0 carat stones of the same quality. No two diamonds are exactly alike, and you must weigh all of the factors - color, cut, clarity and carat weight - when making your buying decision. Our jewelry consultants will gladly give you expert advice to help you find that perfect diamond.

Legends, Myths and Healing Properties:

Click to enlarge image of the Hope diamond. Diamonds have been at the heart of myth and legend since their discovery. Medieval knights wore them uncut on their armor in the belief that they could make a person invincible, a myth no doubt related to the stone's hardness. There are legends of a diamond that could reveal the guilt or innocence of a person. Diamonds could also drive away the devil, and in the days when gems were believed to cure disease and ill fortune, diamonds were thought to amplify the magical powers of other stones a person wore.
Almost universally, diamonds have been associated with virtue, purity, strength, wealth, power, and love - and, not surprisingly, diamonds have been associated with sex, too. So it was a small jump for diamonds to become the modern symbol of love - diamond wedding rings have been popular for hundreds of years. They were believed to ensure fidelity and strengthen emotional bonds. Today, they are the preferred gift for all manner of romantic occasions.
There is one important footnote to the magic of diamonds: the magic is lost if the stone is acquired by purchase. When found or given as a gift, however, it will convey its power to the recipient, which no doubt accounts for how diamonds became such a popular gift between lovers.