The Incomparable was found in the Democratic Republic of Congo (formerly Zaire) in the town of Mbuji Mayi in the 1980s. The rough stone weighed 890 carats, and was found by a young girl playing in a pile of rubble outside her uncle's house. This rubble had been legitimately collected from old mine dumps from the nearby MIBA Diamond Mine, having been rejected during the recovery process as being too bulky to be worth scanning for diamonds. The girl gave the diamond to her uncle, who sold it to some local African diamond dealers, who in turn sold it to a group of Lebanese buyers operating out of Kinshasa.

The stone had several irregularities with cracks and cavities. The proper shaping of the stone took four years. Before cutting, the stone did not display any color variation but the leftovers of the stone showed different colors like deep yellow, pale yellow and brown. Those fragments which had brownish color emerged from the darkest area of the stone but due to the removal of the dark material, the body of the gem has a yellow color.

The Incomparable's 890-carat rough form, left, and the finished Incomparable in its gold ornament stand, right.

The job of overseeing the cutting was given to Mr.Marvin Samuels (who co-owned the stone along with Donald Zale of Zales Jewellers and Louis Glick), renowned for his experience and expertise in the faceting of large diamonds. This diamond showed its fair share of problems. Its basic shape is extremely irregular: it was thicker at one end, narrower at the other; sunken and pitted on one side, ridged on the other. The surface was very rough, pitted with various gaps, cavities and cracks. At least it came as something of a relief that, after a part of the surface had been initially polished and the interior opened up (which is known as "cutting a window") for inspection, It was virtually free of inclusions.

Sampson White's examination caused him to realize that the rough stone had not been uniformly colored, but extraordinarily color-zoned. That is, the crystal had been composed of sharply defined areas of differing colors, each color representing some change in the environment that must have happened as the crystal was growing. At one stage, the stone had been colorless, then nature had added a thickness of pale yellow diamond, followed by a "skin" of smokey amber-colored diamond.

Four years were spent studying and then cutting the stone. Its owners were faced with a dilemma: Should they go for a gem with a weight that would exceed that of the Cullinan I (530.20 carats) or fashion a smaller, flawless gem, by removing the internal inclusions. However, during the course of the second year's work on the stone, Mr. Samuels and the cutters knew it would be necessary to give up any thought of surpassing the weight of the Cullinan I, despite the reluctance of some who continued to argue for size as opposed to perfection.

From the fragments, fourteen satelite gems were cut, the largest being a kite shape of 15.66 carats; the others of varying shapes, weighed 6.01, 5.28, 4.33, 3.45, 3.32, 3.31, two weighing 2.74, 1.99, 1.74, 1.63, 1.52, and 1.33 carats.

The biggest piece of rough ultimately yielded a gem weighing 407.48 carats; It measures 53.90 × 35.19 × 28.18 mm, and has been graded in 1988 by the Gem Trade Laboratory Incorporated as a Shield-Shaped Step Cut, Internally Flawless clarity and Fancy Brownish-Yellow in color. Its unusual triangular shape elicited a new imaginary term from Marvin Samuels -- a "triolette."

The Incomparable, with its satelite stones. The stone
directly in front of it is the 15.66-carat kite-shape

The stone made its first appearance in the year 1984 and on that day the seventy-fifth anniversary of Zale Corporation was being celebrated. The finished stones were put on display: a single golden diamond of 407.48 carats (81.50 g) and the fourteen additional gems.

The Incomparable's very unusual facet pattern, as captured from its Gemcad file.

Prior to its appearance at auction in New York on October 19th, 1988, the diamond was offered at Christie's in London where it was called "the Golden Giant." However, when the gem came up for auction again it had been renamed Incomparable, the largest diamond ever offered to the public for sale. It was hoped the diamond would fetch $20 million but it was withdrawn from sale when bidding failed the seller's reserve price (which actually was $20 million). Either way, history had been made: the late Theodore Horovitz of Geneva, placed a bid for $12 million, the highest price ever bid at auction for a single stone at that time.

Unusually, the Incomparable Diamond even made an appearance on eBay in November 2002, but the word "Incomparable" was never mentioned anywhere in the text of the auction. The diamond remained unsold with a reserve of £15 million pounds sterling. The auction itself was quizically vague and showed a poor-quality photo.

Louis Glick is said to still own the stone to this date.

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