What is kashi? The Persian tile tradition

Kashi is the Persian Islamic tile tradition, the counterpart to Moroccan zellij but produced by different techniques, in different palettes, and with different signature patterns. The name comes from the city of Kashan in central Iran, which became a major centre of glazed-tile production in the medieval period and gave its name to the tradition more broadly. Where zellij is hand-cut mosaic, kashi includes multiple techniques: true cut mosaic (kashi-kari), painted square tiles fired with multiple colors applied through stencil work (haftrang, "seven colors"), and cuerda seca (in which thin lines of greasy substance separate colors during firing). The visual results are some of the most striking surfaces in Islamic architecture, especially the great Safavid mosques of Isfahan and the Timurid monuments of Samarkand.

This post covers what kashi is, how it differs from zellij, the techniques, and where the best examples survive.

What kashi means

In English-language scholarship, "kashi" is used in two related senses. Narrowly, kashi refers to a specific category of glazed tile produced in Iran from roughly the 13th century onward. Broadly, kashi refers to the entire Persian tile tradition, including cut mosaic, painted tile, and cuerda seca methods.

The word kashi itself comes from Kashan, a central Iranian city that was a major producer of glazed pottery and tile in the Seljuk and Ilkhanid periods (11th–14th centuries). Other Persian terms for tile work include kashi-kari (the cut tile mosaic technique specifically) and haftrang (the seven-color overglaze technique).

For the Moroccan counterpart, see what is zellij — a guide to Moroccan tile work.

How kashi differs from zellij

The two traditions look immediately different in person, even if they're often confused in general writing about Islamic art.

Production technique. Zellij is exclusively hand-cut mosaic — individual tiles cut from glazed terracotta into specific polygons. Persian work uses cut mosaic, but the majority of major kashi monuments use square or rectangular tiles with patterns painted across multiple tiles, then fired. This produces a different visual texture: zellij has visible joints between every shape; haftrang has joints only at the square tile edges, with the pattern flowing across them.

Color palette. Zellij is dominated by earth tones (terracotta, brown, ochre), deep blue, green, white, and black. Kashi is famous for its bright turquoise blue and deep cobalt — the palette of the great Safavid mosques. Kashi also uses pure white, yellow, and (in later periods) saturated reds and pinks. The Imam Mosque in Isfahan is the canonical example of the kashi palette at full intensity.

Pattern symmetry. Zellij is dominated by octagonal (8-fold) symmetry, anchored on the khatem star. Kashi is more varied but with a strong tendency toward decagonal (10-fold) symmetry, anchored on the 10-pointed star or 12-pointed variants. The mathematical patterns underlying the two traditions differ; the Persian tradition produces patterns that can be quasi-crystalline, as Lu and Steinhardt's 2007 paper showed (see what is girih).

Combination with arabesque. Zellij is almost exclusively geometric; floral arabesque appears in adjacent media (carved stucco) but rarely in the tile itself. Kashi commonly combines geometric and floral arabesque elements in the same tile work, especially in the Safavid period. The Imam Mosque in Isfahan has surfaces where geometric and floral elements are layered together in a single composition.

The four main techniques

Cut mosaic (kashi-kari). True mosaic, like zellij. Individual tiles cut from monochrome glazed terracotta and set into plaster. The Persian cut-mosaic tradition produced some of the most elaborate work — the Friday Mosque of Isfahan has cut-mosaic panels of extraordinary complexity. Cut mosaic is the most labor-intensive technique and is used for the most prestigious commissions.

Painted square tile (haftrang). Larger square tiles, painted with patterns in multiple colors and fired. The pattern is designed to flow across multiple adjacent tiles, so each tile contains a fragment of a larger composition. This is the dominant technique for the great Safavid mosques. It's faster and cheaper than cut mosaic, which is part of why the Safavids could decorate vast surfaces this way.

Cuerda seca ("dry cord"). A technique where thin lines of a greasy substance separate the different colors during glazing, preventing them from running into each other in the kiln. The result is a painted-tile look but with cleaner separations between colors. Used extensively in Timurid and Safavid work.

Single-color square tile. The simplest technique: monochrome square tiles arranged into patterns by their placement. Often used for backgrounds in dome interiors or for plinths and dadoes.

The signature monuments

A short list of where to see kashi at its peak:

The Friday Mosque of Isfahan (developed across centuries, 8th–17th c.). The single richest concentration of Persian tile in any one building. The mosque includes work from every major Persian period, including the spectacular Ilkhanid stucco mihrab and Safavid kashi panels.

The Imam Mosque (Shah Mosque), Isfahan (1611–1629). The Safavid masterpiece. Built under Shah Abbas I as the centerpiece of his new royal square (Naqsh-e Jahan), the mosque is decorated almost entirely in haftrang tile across vast surfaces. The cobalt-and-turquoise palette is the canonical Safavid statement.

The Sheikh Lotfollah Mosque, Isfahan (1602–1619). Smaller than the Imam Mosque but with the finest tile quality. The dome interior, with its star-burst geometric pattern in turquoise, cream, and cobalt, is one of the most photographed surfaces in Islamic architecture.

The Registan, Samarkand (15th–17th c.). The three madrasahs framing the Registan square — Ulugh Beg, Sher-Dor, and Tilya-Kori — display Timurid and post-Timurid tile work at monumental scale. The Tilya-Kori interior is gilded.

The Shakh-i-Zindeh, Samarkand (14th–15th c.). A complex of mausoleums on a hillside, each decorated with tile in different patterns and palettes. The site is essentially a museum of Timurid tile technique.

The Gur-e Amir, Samarkand (1404). Timur's mausoleum, with the iconic ribbed turquoise dome that has become the visual symbol of Samarkand.

The Darb-e Imam shrine, Isfahan (1453). The site that gave Lu and Steinhardt their 2007 paper on quasi-crystalline tilings. Modest in size compared to the Imam Mosque but mathematically extraordinary.

For more on the Persian regional tradition, see Persian Islamic art — Isfahan, Yazd, and the Safavid flowering.

The living tradition

Persian tile production continues in Iran today, with the cities of Isfahan, Yazd, and Mashhad as the major centres. The techniques used in contemporary restoration of the great monuments are continuous with the medieval practice. Some Iranian ateliers also produce new work for international buyers, including mosque commissions and architectural projects.

Outside Iran, Persian-trained craftsmen have established workshops in several countries, especially in the Gulf states for mosque commissions. Persian tile work is harder to find at scale in Western Europe and North America than the Moroccan tradition, partly because of the political complications of working with Iranian ateliers and partly because the Moroccan tradition has had more sustained Western design exposure.

For an overview of the broader Islamic art tradition, see Islamic geometric art: a complete guide.

FAQ

What is the difference between kashi and zellij?

Kashi is the Persian tile tradition (Iran, Central Asia); zellij is the Maghreb tradition (Morocco, Andalusian Spain). They differ in technique (kashi includes painted square tile and cuerda seca; zellij is exclusively cut mosaic), color palette (kashi favors turquoise and cobalt; zellij favors earth tones and deeper blue), and pattern symmetry (kashi favors decagonal; zellij favors octagonal).

Why is Persian tile work so often turquoise?

Turquoise glazes were achievable in Persian kilns using copper-based glaze chemistries from the medieval period onward. The color has religious significance in Persian culture broadly — turquoise stones were associated with paradise, protection, and divine blessing. The combination of technical capability and cultural preference produced the characteristic Persian palette.

Where can I see the best kashi tile work?

Isfahan in Iran is the primary destination — the Friday Mosque, the Imam Mosque, the Sheikh Lotfollah Mosque, and the Darb-e Imam shrine are all within walking distance of each other. Samarkand in Uzbekistan is the other major site, with the Registan complex, Shakh-i-Zindeh, and Gur-e Amir. The V&A in London, the Met in New York, and the David Collection in Copenhagen all have significant Persian tile holdings for those who cannot travel.

Is kashi tile still being produced today?

Yes. Persian tile production continues in Iran in the cities of Isfahan, Yazd, and Mashhad, using techniques continuous with the medieval practice. Iranian craftsmen also work internationally on mosque commissions, especially in Gulf states. The tradition is alive, though access from Western countries is complicated by political constraints.

Sources

• Wichmann, Brian, and David Wade. Islamic Design: A Mathematical Approach. Springer, 2017. Section 5.3 (Ceramics and Tile), Section 6.3 (Iran).
• Golombek, Lisa, and Donald Wilber. The Timurid Architecture of Iran and Turan. Princeton, 1988.
• Pope, Arthur Upham. Persian Architecture: The Triumph of Form and Color. George Braziller, 1965.
• Necipoğlu, Gülru. The Topkapı Scroll. Getty Center, 1995.
• Met Museum essay, Tilework in Islamic Art.