I think that most people have accepted Trond Noren Isaksen's information: that the elaborate diamond earrings now worn by Queen Sonja are the same as two pendants on necklaces worn by Queen Alexandra.
For Trond Noren Isaksen's 2011 item see http://trondni.blogspot.com/2011/01/royal-jewels-queen-mauds-pearl-and.html
Queen Sonja of Norway wearing the earrings.
Queen Alexandra of Great Britain wearing the necklace with the elaborate pendants. In both of the photos below Queen Alexandra has the pendants beside a central pendant.
Queen Alexandra also wore the pendants attached to her pearl and diamond wedding gift necklace.
Many accept, despite poor photographs and indistinct details in paintings, that the pendants were initially Queen Victoria's Turkish earrings, which she wore for many significant occasions in her earlier years as Queen.
In the only photograph I am aware of the details are blurry.
None of the paintings I have seen of Queen Victoria gives us clear details of the earrings.
Some of the paintings give only an impression of large earrings and in some the details look very different.
I have never been fully convinced that the earrings worn by Queen Sonja match those of Queen Victoria.
Because we don't have a clear image of Queen Victoria's earrings, it is difficult to be sure if the earrings are the same.
I would like to put forward another possibility: that the elaborate pendants on Queen Alexandra's necklaces came from the Duchess of Inverness, the wife of the Duke of Sussex, one of Queen Victoria's uncles.
When she died in August 1873 the Duchess of Inverness left Alexandra, then Princess of Wales, her "long diamond earrings" which, according to the Duchess' codicil, were then kept at her bank. That suggests to me that the earrings were substantial as the Duchess did not mention any of her other jewels as being stored at a bank.
Unfortunately, I cannot find any images of the Duchess of Inverness wearing grand jewels, but her will proves that she did have some major pieces.
It is very hard to date all the photos of Queen Alexandra where she is wearing the elaborate necklace but, from what I can ascertain so far, the elaborate necklace appears in photos only from the early 1880s, which makes it feasible that the pendants are the Duchess' "long earrings".
It is, of course, possible that the earrings did initially belong to Queen Victoria, and it is feasible that she gave them to Queen Alexandra during the former's life time. But, I think we also have to consider the possibility that Queen Sonja's earrings originated with the Duchess of Inverness.
In some respects it seems strange that Queen Alexandra designated such elaborate earrings/pendants for Queen Maud.
Yet, the Duchess of Inverness was a godmother for Queen Maud, and the Duchess left the then Princess one of her diamond rivieres (she had at least 3), so that might explain why the pendants ended up with Queen Maud, both of the jewels having belonged to the Duchess of Inverness.
What a shame that we cannot get access to Queen Alexandra's jewel inventories!!