A friend of mine, who is a jeweler and a researcher, has just started a very interesting blog. Some articles are only in Spanish while others are both in English and Spanish (although it is very easy to get things translated).
I will leave here the link, for the ones interested: https://milstein.jewelry/
I would highlight some of the articles he has already posted like the one about the "mysterious" tiara worn by Queen Anne of Romania, in 1978 in Monaco. As it is something that I recall being discussed on boards for long.
It appears that it was a loan from the Princes of Schaumburg-Lippe. Being worn by various ladies of that family.
Other post that I found really interesting was the one regarding the necklace that was given to Grace Kelly on the occasion of her wedding by the National Council of Monaco.
It appears that the final gift, the well known Cartier diamond necklace was not the first choice and there was a huge troublesome.
In fact, the first choice was a set comprising a necklace, bracelet, ring and double clip in rubies and diamonds, the colors of the flag of the principality. This set was made by Clerc.
What happened was that the intermediary of the sale was found in a sort of scandal! Here you have the link to the article: https://milstein.jewelry/el-affaire-del-collar/