10- and 11-pointed stars
Where the radii of 12- and 9-pointed stars can be drawn in line with each other, it’s not the case with 10- and 11-pointed stars. It takes some fitting work to place them in line as good as possible. The result is a pattern in which more forms are irregular.
This is disturbing in a detailed analysis of the pattern, but you hardly see it in when looking at a building with the pattern on it. Follow stepwise the construction of the pattern as described by Jay Bonner in his book Islamic Geometric Patterns (See references at the end).
surprising
Combination possibilities of star patterns surrounded by not quite regular polygons are almost unlimited and mark a highlight in the development of Islamitic geometric pattern. Remarkably when looking at these patterns you hardly notice that they don’t show just 10- or 12-pointed stars. Only while examining closely you notice how clever more unusual stars are combined. A nice example of this is the Mu'Mine shrine in Nakhchyvan (Azerbeidzjan 1186-87). Only when looking and counting closely you see that it bears 13- and 11-pointed stars in an elegant looking pattern.
