The Decorative Arts
There are two kinds of decorative work done with the marble on the Taj Mahal. One is the relief look, shown in the middle, which is done by cutting away the marble around the intended image to create these beautiful flowers. The second is Agra's famed inlay work, which is done by chiseling out space for the semi-precious stones with a diamond-pointed apparatus, covering the marble with a temporary orange-brown dust to allow the artist to see the image he's cutting, and securing the carefully cut stones into the spaces with a "secret ingredient" glue. The glue is some combination of natural gum, marble dust, and a few other materials that make it impossible to wear down and release the stone. That said, rumor has it that the Taj apparently used to be filled with precious stones that were stolen from the monument... I wonder if they were held in with the same impressive glue!