This group of Prangs stands in front of the temple. The from of a Thai Prang derives from Khmer Prasat. It was built in the reign of King Rama I, the Prangs are of different colours and each one is dedicated to a certain Buddhist concept or a specific element of Buddhism.
We will start with north Prangs and move the south.
1. White for the Buddha
2. Purplish Blue for the Dhamma
3. Pink for the community of Buddhist monk
4. Green for Buddhist Nuns who existed in the ole period
5. Purple for the Pacceka Buddha who has attained enlightenment but not to teach the knowledge to human beings
6. Dark Blue for the Universal Monarchs. (Borommchakkrawatti Raja)
7. Red for the Bodhisattvas who practice great virtues and will be Enlightened and become the Buddha in the next life.
8. Yellow for the Buddha Ariamaittrai, Mahayana Buddhism calls him Maitreya, the future Buddha.


source : Tourist Guide to Thailand book,Thailand-sawasdee.blogspot.com