Britain's Prince William and his wife Catherine, Duchess of Cambridge, pose in the garden of the Middleton family home in Bucklebury, southern England, with their son Prince George, in this undated photograph released in London August 19, 2013. [Photo/Agencies]

LONDON -- The christening of Prince William and Kate's firstborn, Prince George, will be marked with a set of commemorative coins, the Royal Mint said Saturday.

The Duke and Duchess of Cambridge's baby son will be christened at the Chapel Royal at St. James's Palace on October 23, just over three months after his birth. It is the chapel where the coffin of William's late mother, Princess Diana, was put for her family to pay last respects in private before her funeral in 1997.

The production of the commemorative coins, approved by William, his wife Kate and Queen Elizabeth II, will be the first time that new coins are produced to mark a royal christening in Britain.

Buying the coins may be the only way the public can take part in celebrating Prince George's christening, which will be a private event, attended only by close family and the baby's godparents, who haven't been named yet. Official photographs will be released after the ceremony, Kensington Palace said.

"This will be the first formal occasion for Prince George, it will be one in which the baby is welcomed into the Church of England. After all, he will one day become the head of the church, so this is an important ceremony," royal historian Hugo Vickers said.

The event will also see the first official photographs that include the queen and all of her three direct heirs: Charles, William and George.

The venue of the ceremony is a break from recent tradition: William, his father Prince Charles and the queen were all christened at Buckingham Palace, while Prince Harry was christened at St. George's Chapel at Windsor Castle.

The Chapel Royal at St. James' Palace is a lesser known and more intimate venue. Constructed by Henry VIII, it was decorated by Hans Holbein in honor of the king's short-lived marriage to his fourth wife, Anne of Cleves.

The christening of Prince George, who is third in line to the throne, will be conducted by Archbishop of Canterbury Justin Welby. The baby will wear a replica of a christening gown made for Queen Victoria's eldest daughter in 1841.

The 5-pound coins to mark the occasion will be made of solid gold, silver and a more affordable option, and will sell for as much as thousands of pounds (dollars). The designs of the coins have not yet been revealed.