<P> The RockWatch or Rock Watch was a trademarked brand of wristwatch by Tissot with a case essentially made of stone, initially alpine granite from the Grisons, Ticino, and Valais cantons of Switzerland . It was designed by Robert Mazlo and first introduced to the U.S. market in December 1985 and in Switzerland March 1986. Tissot claims it was the world's first wristwatch with a case made of natural stone . The cavities for the movement and dial face were milled from both sides, making the dial an integral part of the case . The straps were fixed to the back plate on both ends thus preventing mechanical stress to the stone . </P> <P> Later versions of the watch used different stones from various mountainous areas around the world including alabaster, aventurine (Brazil), basalt (Scandinavia), blue lace agate, blue sodalite (Brazil), lapis lazuli (Italy), magnesite, picture jasper (Kalahari desert), pink rhodonite (Australia), quartz, and thulite . Some pieces received decorative dial inserts such as sectors from prehistoric clamophyllia coral (Jura mountains) as a premium option . </P>

When was the first natural stone watch created
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