You're welcome!
I had another idea for you - I firmly believe that necessity is the mother of invention so here's an alternative if the chatons are a problem to get a hold of for you, or are too big, or whatever.
I see that the bezel which held the missing crystal is cupped. Not knowing how big a crystal you need, and if wanting to go tinier than 4.5mm, the idea is this -
Swarovski flatbacks are even tiner - I think they start at 2.5mm. You can use them if needed. All you'll have to do is use two-part epoxy, mix it up and with a toothpick pick up a small gob and deposit it in the center of the empty bezel (which you'll have cleaned with alcohol and a Q-tip first). MAKE SURE you have the earring sitting completely flat/horizontal so the glue won't accumulate more on one side or another of the bezel. Add gobs of glue if necessary until your bezel is filled to almost the top, leave yourself maybe half a millimeter of metal without glue. Let the glue set until dry, then glue your flatback in. The two-part inside the bezel will form a cushion on which your flatback can sit without sinking!
For the orange earrings, it would be interesting to know how big around the center cab is. Those look like fiber-optic (cat's eye) cabs and they can be found, but you need to look for that specific size. I have several round cat's-eye cabs but where I buy them they are quite large, 14mm.
Ciao ciao!