"The markings on the backside of this piece indicate that it was once set in something." — Item examination
The Crown Jewel is a treasure item that can be obtained in Chapter 4-1 of Resident Evil 4, by defeating the Verdugo at the end of the chapter. Although being worth 11,000₧ at the Merchant stand when sold on its own, the jewel can instead be fitted with the Crown and Royal Insignia to recreate the Salazar Family Crown. As there is only one Crown Jewel in the entire game, failure to kill the Verdugo and obtain the jewel will mean that the combined piece cannot be made.