Carcanet
Carcanet (kar"kȧ*net) , noun
[Dim. from French carcan the iron collar or chain of a criminal, a chain of precious stones, Late Latin carcannum, from Armor. kerchen bosom, neck, kelchen collar, from kelch circle; or Icelandic kverk troat, Old High German querca throat.]
A jeweled chain, necklace, or collar. — Shakespeare