In Thailand, there is a color for every day of the week
You probably know The color of King Rama X is yellow as it was for His father, that the sky blue is the color of the Queen Mother and may think those are royal colors depending on the rank but not at all ! It depends on the day of birth. In Thailand, every day of the week has its color.
In Thailand, there is one color per day of the week (2 on Wednesdays)
One day, a color …
For Thai the day of the week of their birth is very important. You have surely seen it in the temples, there are Buddhas dedicated to each day with two different statues for Wednesday, one for the day time and one for the evening and night. It’s the only day that has this particularity. And people give donation and prayer to the Buddha corresponding to their day (there is sometimes also a Buddha for those who do not know their day of birth). For the colors of the week, it’s the same pinciple with two separate colors also for Wednesday.
Every day of week is also associated with a type of character that are more likely to have those born that day. A kind of horoscope.
They also have a “bad luck color”. Here is the summary of the colors of each day.
| Day of the week | Color of the day | Bad luck color |
|---|---|---|
| On Monday | Yellow | Red |
| Tuesday | Pink | Yellow or White |
| Wednesday (day) | Green | Pink |
| Wednesday (night) | Grey | Orange or Red |
| Thursday | Orange | Purple |
| Friday | Sky blue | Navy blue or Black |
| Saturday | Purple | Green |
| Sunday | Red | Blue |
Obviously, there are superstitions or at least beliefs linked to this. I do not know how far it goes but I know that my wife was delighted to discover that we were both born on a Thursday and our daughter too.
Now, you can easily deduce that King Bhumibol was born on a Monday, his son King Rama X also, Queen Sirikit, King Bhumibol’s wife on a Friday, and Queen Suthida, king Rama X’s wife, on a Saturday. Almost every Thai has at least one yellow shirt at home to pay homage to the King on certain occasions.
And you know your color now… if you know on what day of the week you came into this world. But it is easily found by typing the date in an Internet search engine.
There are also beliefs about the numbers. So do not be surprised if when you enter into a relationship with a Thai, that your partner wants to know your exact date of birth. It is also not said that he/she will not take you to see a medium to read your future together. I know people who experienced it 
Origins of colors
The color would actually be associated with the protective Hindu gods of each day because, yes, it commes from Hinduism like many elements of Thai culture. Each god is also associated with a star associated with day.
| Day of the week | Divinity | star |
|---|---|---|
| On Monday | Chandra | Moon |
| Tuesday | Mangala | March |
| Wednesday (day) | Budha (by the Buddhist Buddha) | Mercury |
| Wednesday (night) | Rahu | Mercury |
| Thursday | Brihaspati | Jupiter |
| Friday | Shukra | Venus |
| Saturday | Shani | Saturn |
| Sunday | Suriya | Sun |
Source: Wikipedia
The practice is rather obsolete but it still happens that some Thais dress daily depending on the color of the day. When I took my Thai lessons, teachers were dressed in yellow on Monday, pink on Tuesday, green on Wednesday, orange on Thursday and light blue on Friday, for example. So it is still done sometimes but it is true that these colors are mostly used for holidays and events related to members of the royal family of Thailand. And so a new color has been added this year, purple, the color for Queen Suthida.
