The studs feature a main diamond surrounded by four, smaller half-moon shaped clusters of stones, the Windsor Royal Family Instagram account reports.
The American-born royal also chose a white, bespoke Dior dress for her son's special day, which boasted a similar boat neckline to the custom Givenchy bridal gown she wore to walk down the aisle to Prince Harry.
The Sussex's decision to keep their son's royal christening a private affair - with the identities of Archie's godparents a closely guarded secret - has drawn criticism from the British public.
The controversy stems from the $4.3 million AUD renovations the royal couple made on their home at Frogmore Cottage, a bill footed by British taxpayers.
The Duke and Duchess have come under fire since the figure was released by Buckingham Palace late last month, with their move to keep Archie's christening under wraps only angering the public further.
Baby Archie was christened in the private chapel at Windsor Castle by the Archbishop of Canterbury, Reverend Justin Welby, just like his cousin Prince Louis last year.
In the official christening photos taken inside the Green Drawing Room of Windsor Castle by royal photographer Chris Allerton, a smiling Harry and Meghan are seated on an ornate emerald and gold sofa with two-month-old Archie, who is dressed in a replica of the Honiton lace royal christening gown commissioned by Queen Victoria in 1841.
The robe was worn by every royal baby until 2004, when it was replaced by the replica.
The Sussexes are flanked by the Duchess of Cornwall and Kate Middleton, who was said to look uncomfortable and "ready to flee" by royal fans and body language experts.
Prince Charles, Doria Ragland and Princess Diana's sisters Lady Jane Fellowes and Lady Sarah McCorquodale stand behind the chairs, with a 'sour' faced Prince William on the far right.
Queen Elizabeth and the Duke of Edinburgh were notably absent from the royal christening, due to prior commitments for the Queen.