I agree with Franck that the brooch worn by the Queen Mother at Covent Garden Royal Opera House on 1st March, 1960 was probably the emerald and diamond lily brooch, which King George VI presented to her in 1948 to mark their silver wedding anniversary. Queen Elizabeth the Queen Mother wore this brooch both on day outfits and on gala evening gowns.
June 1970, Edinburgh:
February 1981: Visit to the Urban studies Centre Frank Coles House of the College of St Mark and St John
1989: Royal Smithfield agricultural Show in London
7th May 1996: visit to Cynthia Spencer House, Northampton
10th June 2000, Epsom:
Regarding the bracelet, it is really difficult to know. I wonder if it could be the bracelet worn by Queen Elizabeth II during the State dinner given at Windsor Castle for the Irish President Michael O'Higgins on 8th April, 2014, of which we had managed to find out that it was an emerald bracelet, possibly dating back to Queen Victoria - but I confess I am far from being sure!