Adele, you mention vintage pin. It's difficult, to place this jewelry without a photo. If you could upload a photo of the whole pin, it would give the guru team more information to work with.
best Yvonne Hammouda-Eyre
Rating
GW in Rectangle Shape by: Lorraine
GW could stand for gold washed with 14k. The only maker I can find with these initials, could be hallmark GW in rectangle shape is for George Wintle, London 1819.
