Princess Margaretha wore this tiara for a few celebrations in Norway, as well as in Sweden and of course Denmark:
12.01.1961 - Wedding of Princess Astrid, Mrs Ferner 28.08.1968 - Pre-wedding dinner for the then Crown Prince Harald and Sonja Haraldsen 29.08.1968 - Wedding of Crown Prince Harald and Sonja 02.07.1973 - 70th birthday of King Olav V (Dinner hosted by the Government)
In Sweden: 10.12.1967 - Nobel Prize ceremony
In Denmark: 13.01.1968 Wedding of Count Ingolf of Rosenborg and Inge Terney
This is of course an incomplete list and I am certain that it has been worn in many more occasions. However, so far they are the ones I have discovered. If anybody could help me to add more occasions to the list it would be very much appreciated.