The marble inlay technique used extensively in the Taj Mahal is called pietra dura. In Mughal India, the same style is commonly known as parchin kari, or parchinkari, meaning inlay work.
Artisans cut coloured stones into precisely shaped pieces and fitted them into recesses carved in the white marble. The resulting designs depict stylised flowers, vines, fruits and geometric forms. Unlike a painted decoration, the colour comes from the stones themselves, which are polished until the surface becomes nearly level and the joins are difficult to see.
The Taj Mahal’s decoration uses many kinds of precious and semi-precious material. Historical descriptions identify 28 types of stone, including jade from China, turquoise from Tibet, lapis lazuli from Afghanistan, sapphire from Sri Lanka and carnelian from Arabia. The work appears throughout the gateway, walls, cenotaph screen and interior surfaces.
Intarsia is a broader term for fitted inlay, while mosaic usually uses smaller pieces set into a surface. “Filigree” refers to delicate metal wirework, so it describes a different craft entirely.