Question: Gérald Genta, a Swiss jewelllery designer, worked with what luxury Swiss watch manufacturer which was founded by American Watch,aker Florentine Ariosts Jones?

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Constant Girard
Constant Girard (La Chaux-de-Fonds 1825 – 1903 La Chaux-de-Fonds) was a Swiss watchmaker from the 19th century, who marked his time by his developments in the escapement systems, in particular that of the tourbillon.
 His most famous watch, the Tourbillon with three gold bridges, is still fabricated today in modern versions by the Swiss watch manufacturer, Girard-Perregaux.
Juvenia
Juvenia is a luxury Swiss watch manufacturer located in La Chaux-de-Fonds, Switzerland.
 It is one of the few Swiss watch companies to have manufactured watches without interruption since its creation.
 The brand is currently owned by Hong Kong group Asia Commercial Holdings Ltd.
Hamilton Watch Company
The Hamilton Watch Company is a brand of the Swatch Group, a Swiss watch company based in Bienne, Switzerland.
 The Hamilton Watch Company had its genesis as an American watch design and manufacturing company, which incorporated in 1892 and produced its first watch in 1893.
Gérald Genta
Charles Gérald Genta (1931-2011) was a Swiss jewellery designer, noted for his eponymous line of time pieces as well as his design work with other firms, including IWC, Universal Genève, Patek Philippe and Audemars Piguet, among others.
 Christie's auction house of New York called Genta's work ""the Fabergé of watches"", while "The Wall Street Journal" has called them the "world's most complicated and pricey watches".
Patek Philippe &amp; Co.
Patek Philippe & Co. is a Swiss watch manufacturer founded in 1851, located in Geneva and the Vallée de Joux.
 It designs and manufactures timepieces and movements, including some of the most complicated mechanical watches.
 It is considered by many experts and aficionados to be one of the most prestigious watch manufacturers.
Lemania
Lemania was a Swiss watch manufacturer and manufacturer of watch movements.
Memorigin
Memorigin is a Hong Kong manufactured watch brand, which was founded by William Shum in 2011.
 The brand specializes in tourbillion watches, which are often associated with luxury Swiss watch brands.
 The tourbillion movement is only manufactured in a handful of factories worldwide, traditionally retailing at high five or six figure prices (USD).
 Memorigin's founder decided that he could produce a quality mid-range tourbillion, which he would sell directly into the growing Chinese watch market.
Ulysse Nardin
Ulysse Nardin is a luxury Swiss watch manufacturer founded in 1846 in Le Locle, Switzerland, which has remained in continuous production since.
 Ulysse Nardin has operated out of the same building headquartered in Le Locle, Switzerland since 1865.
 Historically, the company is best known for its manufacture of highly accurate marine chronometers supplied at one point during the 1800s to over fifty of the world's navies.
E. Gluck Corporation
E. Gluck Corporation is an American watch manufacturer headquartered in Little Neck, New York.
 It was founded in 1956 by its current President, Eugen Gluck.
 E. Gluck Corporation manufactures watches under two flagship brand names, Armitron and Anne Klein.
 As of 1999, Armitron had the fifth largest share of all watch purchasers, by brand, in the United States.
 As of 2005, Armitron ranks as one of the top ten fine and fashion watch brands in the US, along with Timex, Fossil, Seiko, Citizen, Casio, Guess, Bulova, Movado, and Pulsar.
International Watch Company
International Watch Co., also known as IWC, is a luxury Swiss watch manufacturer located in Schaffhausen, Switzerland, and founded by American watchmaker Florentine Ariosto Jones in 1868.

Answer: International Watch Co.