To be perfectly honest with you, I was very tempted to title this post "Luxarazzi 101: Those earrings especially Maria Teresa and Stéphanie seem to be swapping back and forth an awful lot (and I'm not even sure what they are made of)" but alas that post title was a bit long. So, I'll simply call these the Small Amethyst Earrings (though I'm still not entirely sure what they are made of as the colouring does change quite a bit depending on the lighting).
And while we may never learn what exactly the centre stone surrounded by small diamonds of this pair of earrings is, they still are making the rounds in the family. At least Grand Duchess Maria-Teresa, Princess Alexandra and Hereditary Grand Duchess Stéphanie have worn them in the past. I haven't done maths or anything, but they might just be the most sported earrings of the Grand Ducal Family, worn by both Maria Teresa and Stéphanie on a very regular basis. In fact they are so popular that the former Countess Stéphanie de Lannoy wore them on the day of her civil wedding for a reception (right) and Grand Duchess Maria Teresa a day later for the religious wedding (left).