DIAMOND - April Birthstone

Introduction:  A diamond (from the ancient Greek ἀδάμας – adámas, meaning "unbreakable", "proper", or "unalterable") is one of the best-known and most sought-after gemstones. Diamonds have been known to mankind and used as decorative items since ancient times; some of the earliest references can be traced to India. The hardness of diamond (Mohs’ hardness of 10) and its high dispersion of light (Refraction index of 2.417)—giving the diamond its characteristic "fire"—make it useful for industrial applications and desirable as jewelry. Diamonds are such a highly traded commodity that multiple organizations have been created for grading and certifying them based on the four Cs, which are color, cut, clarity, and carat. Other characteristics, such as presence or lack of fluorescence, also affect the desirability and thus the value of a diamond used for jewelry. 

  The most famous use of the diamond in jewelry is in engagement rings. The practice is documented among European aristocracy as early as the 15th century, though ruby and sapphire were more desirable gemstones. The modern popularity of diamonds was largely created by De Beers Consolidated Mines Ltd., which established the first large-scale diamonds mines in South Africa. Through an advertising campaign beginning in the 1930s and continuing into the mid-20th century, De Beers made diamonds into a key part of the betrothal process and a coveted symbol of status. The diamond's high value has been the driving force behind dictators and revolutionary entities, especially in Africa, using slave and child labor to mine blood diamonds to fund conflicts. Though popularly believed to derive its value from its rarity, gem-quality diamonds are quite common compared to rare gemstones such as Alexandrite, and annual global rough diamond production is estimated to be about 130 million carats (26 tonnes).[1] The value of diamonds is attributed largely to the industry's tight control over this supply.” (Ref-1, Wikipedia 03/23/17) 

  On the net, additional information on diamonds can be found in 1934 different articles from the Gemological Institute of America (GIA), (Ref-2). Books on diamonds can be found at the following web-sites: https://www.cheapestbookprice.com/, or http://www.lithographie.org/bookshop6.htm. A   couple of the best books on diamonds for the rockhound are “The Nature of Diamonds” (Ref-3), and “Diamonds, The Ultimate Gemstone” (Ref-4). 

The Four C's of Diamonds

Diamond Color

 Diamonds in the normal color range are colorless through light yellow and are described using the industry’s D-to-Z color-grading scale. Fancy color diamonds, on the other hand, are yellow and brown diamonds that exhibit color beyond the Z range, or diamonds that exhibit any other color face-up. These rare specimens come in every color of the spectrum, including; most importantly, blue, green, pink, and red. “In the 1960s, the GIA began introducing nomenclature to describe the fancy color diamonds, which exhibit colors that fallout of the D to Z color scale. This system has evolved through the years and today evaluates the “color appearance” of a diamond based on the combined characteristics of “hue (the appearance of red, blue, green, or anything in between), tone (the relative lightness or darkness of a color), and saturation (the relative strength or weakness of a color).“  The vast majority of natural, fancy color diamonds are not particularly intense, but those rare diamonds that exhibit strength and purity of almost any hue  have proven of the most valuable of gems. The GIA’s colored grading system first describes the diamond’s tone and saturation (both of which are, of course, hue dependent) with a grade of “fancy light,” “fancy,”  “fancy intense,” “fancy vivid,” “fancy dark,” or “fancy deep” and then assigns it one of 27 hue names.” (Ref-4, Lithographie)   

World Records for Diamonds

  The world's largest blue diamond, an extremely rare gem known as "The Oppenheimer Blue", sold for $57.5 million at Christie's Geneva May 18, 2016, making it the most expensive diamond ever sold at auction. (Ref-5, Google) 

“The previous record holder for the most expensive diamond was the 24.78-carat Graff Pink, sold by Sotheby's for $46.2 million in 2010.   

In 2013, Sotheby's auctioned a pink diamond called the 'Pink Star' for $83.2 million, but the buyer ultimately defaulted on the payment. The stone remains in the auction house's inventory.   

In (03/25/17), a 1,111-carat diamond was discovered in Botswana by the Lucara Diamond firm. It's currently the world's second largest diamond of gem quality.   

Sotheby's 'perfect' 100-carat diamond sells for $22 million” (Ref-5, Google) 

Diamond Cut:

 “A diamond’s cut is crucial to the stone’s final beauty and value. And of all the diamond 4Cs, it is the most complex and technically difficult to analyze. To determine the cut grade of the standard round brilliant diamond – the shape that dominates the majority of diamond jewelry – GIA calculates the proportions of those facets that influence the diamond’s face-up appearance. These proportions allow GIA to evaluate how successfully a diamond interacts with light to create desirable visual effects such as:   

    * Brightness: Internal and external white light reflected from a diamond

* Fire: The scattering of white light into all the colors of the rainbow 

             * Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond

   GIA’s diamond cut grade also takes into account the design and craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.  

The GIA Diamond Cut Scale for standard round brilliant diamonds in the D-to-Z diamond color range contains 5 grades: Excellent, Very Good, Good, Fair, and Poor.” (Ref-2, GIA  

Diamond Clarity:

 “The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10× magnification.   

Flawless (FL) - No inclusions or blemishes are visible to a skilled grader using 10× magnification. 

Internally Flawless (IF) - No inclusions and only blemishes are visible to a skilled grader using 10× magnification.

Very, Very Slightly Included (VVS1 and VVS2) - Inclusions are difficult for a skilled grader to see under 10× magnification.

    Very Slightly Included (VS1 and VS2) - Inclusions are minor and range from difficult to somewhat easy for a skilled grader to see under 10x magnification 

Slightly Included (SI1 and SI2) - Inclusions are noticeable to a skilled grader under 10x magnification.

Included (I1, I2, and I3) - Inclusions are obvious under 10× magnification and may affect transparency and brilliance”  (Ref-2, GIA)  

Diamond Carats:

 “Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.)

Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, color and cut. The majority of diamonds used in fine jewelry weigh one carat or less.

Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred thousandths of a carat, and rounded to a hundredth of a carat.  Diamond weights greater than one carat are expressed in carats and decimals. (Ref-2, GIA) 

The World's Greatest Diamonds

 The diamonds that are called great are both physically large, usually more than 50 carats for near colorless stones or 30 for blues and pinks, and have an additional claim to fame, such as their history, cut, uniqueness, or their magnificence.    

1. The Hope: A 45.52 carat cushion-cut blue diamond at the Smithsonian, originally a 110.5-carat stone from India purchased for Louis XIV by Jean-Baptiste Tavernier in 1668.   

2.   The Regent:  A 140.5 carat cushion-cut clear, yet faintly blue, diamond. The original 410 carat stone was found In 1698 by a slave in the Kollur Mine in India. The slave stole the diamond by hiding it inside a large wound in his leg.  An English sea captain stole the diamond from the slave, killed him and sold it to an Indian merchant. After passing through many hands, it wound up in the French Louvre.  

3. The Sancy:: This pale-yellow pear-shaped diamond weighing 55.23 carats has a bewildering history. Its origin in India is lost, so the tale begins with the French diplomat Nicolas Harlay de Sancy (1546-1627) who acquired several diamonds including the Great Sancy either through the Ottoma Court in Constantimople or via DSom Antonio, prior to Crato and claimant to the throne of Portugal. After passing through dozens of hands over the years, in 1978, it was sold to the Banque de France and Musees de France for a reported $1,000,000. The Sancy diamond now resides with the Regent in the Louvre. 

 4. The Tiffany: A yellow octahedron weighing 287.42 carats was discovered in the early stages of mining in Kimberly, South Africa, probably at the Kimberly mine in 1877 or 1878. The Tiffany Yellow Diamond is one of the largest yellow diamonds ever discovered The crystal was shipped to Paris, where George E. Kunz, the famed American gemologist who worked for Tiffany & Co., supervised the cutting of the rough into a 128.54 carat canary yellow cushion with a total of 90 facets. Tiffany bought the stone in 1879. The stone still resides with Tiffany in New York City. 

5.    The Koh-i-Noor: The Koh-i-Noor (Persian for Mountain of Light; also spelled Kohinoor and Koh-i-nur) is a large, colorless diamond that was found near Guntur in Andhra Pradesh, India, possibly in the 13th century. According to legend, it first weighed 793 carats (158.6 g) uncut, although the earliest well-attested weight is 186 carats (37.2 g); it was first owned by the Kakatiya dynasty. The stone changed hands several times between various feuding factions in South Asia over the next few hundred years, before ending up in the possession of Queen Victoria after the British conquest of the Punjab in 1849.   

In 1852, Prince Albert, the husband of Queen Victoria, unhappy with its dull and irregular appearance, ordered it cut down from 186 carats (37.2 g). It emerged 42 percent lighter as a dazzling oval-cut brilliant weighing 105.6 carats (21.12 g) and measuring 3.6 cm x 3.2 cm x 1.3 cm.[3] By modern standards, the cut is far from perfect, in that the culet is unusually broad, giving the impression of a black hole when the stone is viewed head-on; it is nevertheless regarded by gemmologists as being full of life.[4] As the diamond's history involves a great deal of fighting between men, the Koh-i-Noor acquired a reputation within the British royal family for bringing bad luck to any man who wears it. Since arriving in the country, it has only ever been worn by female members of the family.[5]  

Today, the diamond is set in the front of the Queen Mother's Crown, part of the Crown Jewels of the United Kingdom, and is seen by millions of visitors to the Tower of London each year. 

The Cullinan:

 The Cullinan Diamond is the largest gem-quality rough diamond ever found, weighing 3,106.75 carats (621.35 g), discovered at the Premier No. 2 mine in Cullinan, modern-day South Africa, on 26 January 1905. It was named after the chairman of the mine, Thomas Cullinan.  

It was presented to King Edward VII of the United Kingdom for his 66th birthday and cut into several polished gems, the largest of which is named Cullinan I or the Great Star of Africa, and at 530.4 carats (106.08 g) it is the largest clear cut diamond in the world. It was the largest polished diamond of any colour until the discovery in 1985 of the Golden Jubilee Diamond (545.67 carats (109.13 g)), also from the Premier Mine. Cullinan I is mounted in the head of the Sovereign's Scepter with Cross. The second-largest is Cullinan II or the Second Star of Africa; at 317.4 carats (63.48 g) it is the fourth-largest cut diamond in the world, and is mounted in the Imperial State Crown. Both diamonds are part of the Crown Jewels which belong to the monarch in right of the Crown. Seven other major diamonds cut from the original weighing a total of 208.29 carats (41.66 g) are privately owned by Queen Elizabeth II, who inherited them from her grandmother, Queen Mary, in 1953 along with ninety-six minor stones. (Ref-3, Harlow) 

World Diamond Resources

 The world’s annual diamond production is listed by country from 1870-2015 on pages 20-  21 in “Diamonds, The Ultimate Gemstone” (Ref-4). In 2015, the biggest producer was Russia at 41.91 million carats. The second and third largest producers were Botswana at 20.78 million carats and DR Congo at 16.2 million carats. By continent, in 2015, Africa produced 47% of the world’s production, Russia 33%, Australia 11%, and North America (Canada) 9%.  In 1989, the Argyle Mine in Australia produced  37% of the world’s production; however, only 5% was gem quality. The hallmark of the Argyle Mine is pink diamonds; and rarely red diamonds, which both sell for fabulous amounts of money. In 2013 the 1.56 carat red Argyle Phoenix diamond, pictured below, sold for over $2 million. 

The North American Diamond Resources

 The main resources are in the Northwest Territories (NWT) of Canada. In 1998, the Ekati diamond mine near Lac de Gras was officially opened; this highly remunerated mine exploits a diamondiferous kimberlite pipe which is one of about 75 pipes scattered about this part of the “Barren Lands” of the far Canadian north, 300 km north of Yellowknife.. The mine promises to become a major world source of diamonds, and gem-quality crystals to 4 carats weight had been reported by the mid-1990s. (Ref-6, Moore)

The Diavik Diamond Mine has become an important part of the NWT regional economy, employing 1,000, and producing approximately 7 million carats of diamonds annually. The area was surveyed in 1992 and construction began in 2001, with production commencing in Jan., 2003. It is connected to points south by an ice road and Diavik Airport with a 1,596 m gravel runway regularly accommodating Boeing 737 jet aircraft. In December 2015, Rio Tinto announced discovery of the 187.7 carat Diavik Foxfire diamond, one of the largest rough gem quality diamonds ever produced in Canada. (Ref-1, Wikipedia) 

United States Diamond Resources

 Colorado: In the mid-1960s geologist became focused on a series of unusual rock deposite along the Front Range of the Rocky and its topographic extension into Wyoming. These rocks turned out to be kimberlites, typically filled with crustal xenoliths. Within a decade, more than 90 kimberlite pipes and dikes had been identified. (Ref-7, Collins, USGS)

For a brief period in the 1990s diamonds were extracted from two of the pipes, and 21,000 carats in diamonds were recovered. The largest diamond mined was a 28.3 carat yellow crystal, christened the Colorado Diamond. (Ref-4, Harris/Staebler) 

Arkansas: Crater of Diamonds State Park, Murfreeboro, Pike County. The first verified, and still the largest, diamond-production deposit in the United States is the intrusive of lamproite rock (a relative of kimberlite) near Murfreesboro, Arkensas. Now one of the states’ major tourist attractions, Crater of Diamonds State Park is a field of weather lamproite where, for a small fee, one may scour and screen for diamonds and keep whatever one finds. The first diamonds were found in 1906 by John Huddleston. Sporadic commercial mining until 1940 was uneconomical, despite occasional dramatic finds such as the 40.23 carat “Uncle Sam” diamond in 1924. (Ref-6, Moore)

A number of beautiful canary-colored diamonds have been found at the Park. The most famous is the "Okie Dokie Diamond"  found in 2006 by Marvin Culver. This 4.21 carat diamond was featured in a number of television programs and magazine articles. 

  An article in Ref-4, pages 87-93 list 25 of the largest diamonds found at Crater of Diamonds State Park from 1924 to 2011. People still occasionally find significant diamonds. On March 16, 2017, a teenage boy discovered a 7.44 carat diamond at the park. Officials at Crater of Diamonds State Park at Murfreesboro say the rock found Saturday by 14-year-old Kalel Langford is the seventh largest found since the park was established in 1972. The park hasn't provided an estimate of the diamond's value. Since the park opened in 1972 for fee digs, over 3 million visitors have recovered more than 30,000 natural diamonds. Park data suggests that it takes about 100 houres of searching for each diamond discovered.    

Another excellent article on the Crater of Diamonds State Park can be found in the Mineralogical Record, Vol. 21, #6, Nov.-Dec., 1990, pages 545-555, by A. L. Kidwell. (Ref-8) 

Montana: An article by J. C. Zietner (Ref-9) provides some details of the July 1990 discovery of a light yellow transparent 14-ct diamond along a road near Craig, Montana, by local “rockhound” Darlene Dennis. The stone was first identified by a local faceter; the  identification was then confirmed by the owner of the Yogo Sapphire mine. According to the article, an additional large (8-ct) stone was allegedly recovered in late 1990 by another Craig resident. The 14-ct diamond was sold for $80,000 to New York gallery-owner Alexander Acevedo. The article includes a color photo of the stone (see below), a discussion of the possible source and future prospects for diamonds from this area, and an insert on diamonds from the Great Lakes region of the U. S.   


 1. Wikipedia 03/23/17) 

2. Gemological Institute of America (GIA),  https://www.gia.edu/

3. “The Nature of Diamonds”, George E. Harlow, et al, American Museum of Natural History, 1998 

4. “Diamond, the Ultimate Gemstone, Jeff W. Harris & Gloria A. Staebler, Lithographie, 2017 

5. Google, 03/25/17 

6. Moore, “Moore’s Compendium of Mineral Discoveries, 1960-2015”, 1916

 7. Collins, Donley S., USGS,  “Mineralogical Record”, Vol. 13, #4, Jul-Aug, 1982 

8.   Kidwell, A. L., “Murfreesboro, Arkansas”, “Mineralogical Record”, Vol. 21, #6, Nov-Dec, 1990 

9. Zeitner, J. C., “The Lewis and Clark diamond”, Lapidary Journal, Vol. 45, No. 5, August, 1991, pp 79-88.