Grotty old Plaid Brooch

[Third Tankie]

Hi Gents,

Found this tired, abused old plaid brooch in my crap/unknown box. Slight cleaning to the front revealed Argyll and Sutherland Highlanders on the scroll. Further cleaning on the rear revealed a very shiny silver surface but no markings, cleaning on the rim uncovered the same.
I have always been intrigued with the heaviness of the brooch and now wonder if it could be silver. The weight is 4.5 oz
I would welcome any comments or opinions even if it is to tell me that I wasted £2.50 on an impulse purchase.................again