Kate, Princess of Wales, wore an iconic 12-carat oval sapphire engagement ring that once belonged to Princess Diana.

The royals are tight-lipped about the day-to-day locations and routines regarding their jewelry.

Royal jewelry pieces have been the target of thieves for generations.

The Princess has been concerned about the safety of her ring in the past.

Royals travel with security and are usually extra careful about how they travel with any valuables.

Kate was seen wearing the engagement ring during a scuba diving session in the Caribbean.

An anonymous source said the royals follow a mantra that the safest place for a ring when traveling is on the hand.

Kate removed her engagement ring during a recent hospital visit for "hygiene reasons."

The royals' jewelry habits may never truly be known.