"It's a Red Jewel that was attached to a Choker."
Alexia's Jewel is an item in Resident Evil CODE:Veronica.
It is the third Ashford family jewel needed to access the hidden part of the mock-up Spencer Mansion in Umbrella's Antarctic Base. It is easily identified by its red twinkle. Setting it in the Ashford family portrait, along with Alfred's Jewel and Alexander's Jewel, opens the secret door to Alexander's lab.
It can be recovered from Alexia's body after she is incapacitated from her first fight with Chris in the mock-up Main Hall.