A beautiful vintage modernist Celtic-style brooch. It is fully hallmarked to the reverse with the maker's name 'MG' then assay marks for Edinburgh Sterling 925 silver, then a 'D' for 1978. It's in a modernist retro style and features curly 70s-inspired Celtic shapes with openwork. MG is Malcolm Gray for Ortak, Orkney, Scotland (the hallmark being hard to read, I'd wondered if it was Ola Gorie's OMG mark initially).
Very good shiny condition. Roll-over pin works well. A nice size, flat, simple, slimline and noticeable: 4 x 4cm, weighs 10g. 
Price includes P&P to the UK. Comes in a presentation box - perfect gift idea.