Powdered black marble dust, mixed with resin, outlines floor tiles with polished inlays of golden-yellow and kiln-baked-red sandstone. The 4x12 designs are custom cut by hand in India, according to a pen-and-ink of palms, by the New York artist Robert Kushner. 833 Broadway, New York, NY 10003; 212-228-8396; sanastoneny.com.