A new stamp featuring Prince Christian of Denmark has been released to mark his upcoming 18th birthday. The stamp was issued by the Greenlandic postal service and telecommunications company, Tusass.

Crown Princess Mary and Crown Prince Frederik’s eldest child is seen wearing a white anorak in the stamp. “The traditional white anorak that Prince Christian wears in the photo is the upper part of the male version of the Greenlandic national costume. Prince Christian’s father, HRH the Crown Prince, his grandfather, Prince Henrik, and his great-grandfather, Frederik IX, have all worn the Greenlandic anorak during their visits to Greenland as well as on a number of historical stamps,” the Danish Royal House noted.

The Royal House shared a video on Thursday of the first letter with the stamp being mailed to Christian from Nuuk, Greenland to Amalienborg in Copenhagen.

Prince Christian, who is second in line to the Danish throne, turns 18 on Sunday, Oct. 15. The royal’s milestone birthday will be celebrated with a changing of the guard at Amalienborg. Christian will also appear on the balcony of Frederik VIII’s Palace with his family and grandmother, Queen Margrethe II. Prince Christian is the oldest of the Crown Prince Couple’s four children. Mary and Frederik are also parents to Princess Isabella, 16, Prince Vincent, 12, and Princess Josephine, 12.

On Sunday evening, Queen Margrethe will host a gala dinner at Christiansborg Palace for Christian. Confirmed guests include Princess Ingrid Alexandra of Norway, Princess Elisabeth of Belgium and Crown Princess Victoria of Sweden.