Medievalists.net has an extremely interesting article about King John and his love of both ceremonial and personal jewellery, including pieces that were talismans.
The article can be read at The Magical Gemstones of King John of England
There is more about the King, his appearance, his possessions, his clothes, his court, and the cultural milieu he inhabited in an online article from 2015 which can be read at KING JOHN'S BLING
On the basis of this evidence the loss of his baggage train in The Wash in 1216 must have been all the more destabilising for an already sick man.
His love of jewellery is indicated clearly in the effigy created a few years after his death in his beloved Worcester Cathedral where he had requested burial. If one mentally fills the depressions in his crown and collar with paste stones one can begin to envisage how the effigy once looked and, by extension, what the King looked like in life.
