Page:A treatise on diamonds and precious stones including their history Natural and commercial.djvu/158

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SARD AND ONYX.

finest touch or stroke of the tool without chipping, and shewing the art of the engraver to the highest perfection.

Any stone exhibiting layers of two or more colors, strongly contrasted, is called Onyx[1]: as banded jasper, chalcedony, &c. but more particularly the latter, when it is marked with white, and stratified with opaque and translucent lines. But the oriental onyx is considered a substance consisting of two or more layers or bands of distinct and different colors. A sard or sardoine, having a layer of white upon it, would be called an Onyx; and according to the number of layers, it would be distinguished as an onyx with three or more



  1. This stone derives its name from the resemblance which some varieties bear to the marks on the finger nail, and has been extended to all stones haying a banded appearance.