by James Hudspeth on 3/28/2022

The World’s Great 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.

The Regent:

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.

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 3. 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.


by Wayne Farley

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)

Diamond Information:  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 Cs 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.

Fancy Color Diamonds

World Records for diamonds:

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.

This week (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)