Thais are changing colors as fast as 79-year-old King Bhumibol Adulyadej dons a green polo shirt after emerging in public in a pink blazer. Public demand turned green after His Majesty the King appeared in a green jacket on his return to Siriraj Hospital on Tuesday to visit his elder sister, Princess Galyani Vadhana.

Last week, pink was in after the king emerged from hospitalization in a pink blazer.

Pink is considered auspicious and green can help bring success for a person born on a Monday. The king, the world's longest living monarch, was born on a Monday - that's why Thais have been wearing yellow in the past year because it is also an auspicious for the day.

''I received at least 30 orders in the morning. By late afternoon, I picked up two sample green shirts from Bo Bae market and wore one as a sales promotion. I sold the other one immediately for 250 baht ($8),'' Somying Puangjinda, 26, a retailer at Pran Nok pier close to the hospital, told the Bangkok Post.

When the first lot of 50 green polo shirts arrived, she sold 10 in just 20 minutes.