Metal detecting is not a public right and as such it needs the permission of the landowner. The PLA and the Crown Estate are the largest land owners of Thames foreshore and jointly administer a permit which allows metal detecting and digging.
Why are there garnets in the Thames?
Hazel Forsyth, a senior curator at the Museum of London who has extensively researched gemstones and has written a book about the Cheapside Hoard jewels, believes that, “the garnets presence on the foreshore is probably due to accidental loss of a shipboard consignment.” She believes that some of the Thames garnets