This is an auction for an original late 19th century Silver Gilt mounted hard enameled Pre-Raphaelite plaque in the style of possibly Edward Burne-Jones or Albert Joseph Moore, the plaque is very well painted and is wonderfully enameled, my first guess is its possibly a Swiss enamel but at this period the English Art house Guild artists also produced some wonderful enamel work? The fact it has what looks to be a simple continental mount and its in the English taste I feel its possibly Swiss but will stand correction, either way its hand painted and not transfer printed, its hard enamel as well so exactly what you would want to see, I think its enamel on Copper and its the brooch mount which is Silver.
The brooch is the other thing which makes me feel its possibly a swiss enamel as its got a very pale washed Gilding which is exactly what you see on Swiss gilding of this period in horology and other Swiss gilding, its almost a weaker guilding but all original and great quality.