An interesting discussion and great photos. Thank you 😊
You are probably just counting the ones owned by the main branch of the royal family, but I thought it was worth mentioning that it seems that the Haga princesses have a collet necklace each.

Margaretha and Desiree each wore one for Victoria’s wedding, and Birgitta’s daughter also wore one. Of course they can have a different provenance, but maybe one of the longer ones from the collection was divided up? Or they had an even bigger collection of collet necklaces earlier. I don’t think these three collet necklaces were borrowed for the occasion.