The Collaborative International Dictionary
Pietra dura \Pi*e"tra du"ra\ [It., hard stone.] (Fine Arts) Hard and fine stones in general, such as are used for inlay and the like, as distinguished from the softer stones used in building; thus, a Florentine mosaic is a familiar instance of work in pietra dura, though the ground may be soft marble.
Wiktionary
n. (context arts English) Hard and fine stones in general, as used for inlay etc. and distinguished from the softer stones used in building.
Wikipedia
Pietra dura or pietre dure (see below), called parchin kari or parchinkari in South Asia, is a term for the inlay technique of using cut and fitted, highly polished colored stones to create images. It is considered a decorative art. The stonework, after the work is assembled loosely, is glued stone-by-stone to a substrate after having previously been "sliced and cut in different shape sections; and then assembled together so precisely that the contact between each section was practically invisible". Stability was achieved by grooving the undersides of the stones so that they interlocked, rather like a jigsaw puzzle, with everything held tautly in place by an encircling 'frame'. Many different colored stones, particularly marbles, were used, along with semiprecious, and even precious stones. It first appeared in Rome in the 16th century, reaching its full maturity in Florence. Pietra dura items are generally crafted on green, white or black marble base stones. Typically the resulting panel is completely flat, but some examples where the image is in low relief were made, taking the work more into the area of hardstone carving.
Usage examples of "pietra dura".
Turn-of- the-century furniture filled the picture window: a red velvet sofa with gold piping trimmed with tassels, a hand-carved Italian chestnut chair with dragon arms, and a small Pietra Dura end table with a black marble top.
But about the Black Birdyou'll recall what I told you of de Castries's pietra dura ring of mosaicked black semiprecious stuff depicting a black bird?
In the sunlight of late afternoon it looked like one of the pietra dura inlays at which Florentine craftsmen excelleda picture shaped from antique gold and semi-precious stones, amber and carnelian, topaz, heliodor, and chrysoberyl.