Items marked ``Sterling`` are most likely not
For example, so called Sweetheart brooches of British Army corps and regiments, popular during WWI and WWII, are still a mystery to me.
Some of them are fully hallmarked by British assay offices, but most of them are marked ``Sterling`` or ``Sterling silver` ` or ``Silver``.
They must have been made overseas (Canada, Australia, South Africa).
Examples: King's Royal Rifle Corps fully hallmarked in Birmingham 1916.
RAF badge with ``Sterling`` only. King's crown indicates it was made before 1953 when Queen Elizabeth II was crowned.