During the christening, Prince Fredrik Adolf's crown stood at the altar.
Gustav III had crowns made for his siblings, Prince Karl (XIII), Prince Fredrik Adolf and Princess Sofia Albertina, for his coronation in 1772. The crowns were made by Court Jeweller Johan Adam Marcklin.
The crowns are made from gold, and are set with pearls and precious stones. The gold used to make the crowns was taken from a toilette service that once belonged to Ulrika Eleonora the Elder, "so as not to burden the realm's funds".
The crowns can be seen in the Treasury at the Royal Palace of Stockholm.
Find out more about the Treasury here.
From 1778 until The King's christening in 1946, Swedish princes received the insignia of the Order of the Seraphim on the occasion of their christening. However, issuing orders to Swedish citizens was abolished by the Order Reform of 1975. In 1995, the law was rewritten to allow members of the Royal Family to receive the Order of the Seraphim. That same year, The Crown Princess received the order on coming of age.
Just as Princess Estelle, Princess Leonore, Prince Nicolas and Prince Oscar received the Order of the Seraphim on their christenings, so too will Price Alexander receive the order at his christening on 9 September 2016.
Find out more about the Order of the Seraphim here.