Carlton House Antiques has dated this Antique Citrine Gold Brooch to the 1920s.
Since then all gold pieces produced must be stamped with a hallmark by the manufacturer. The lack of hallmark on this brooch shows its rarity and age. The markings are not completely clear but seem to read:
N/S m|x - 1000
Carlton House Antiques has dated this Antique Citrine Gold Brooch to the 1920s.
You can view the stock and full dealer information on the Carlton House Antiques Profile Page