I doubt it. It would be like asking VCA to extend a non-VCA necklace. The brands are not in the business for generic jewelry service & repairs. They only want to service their own brand. You can always go to your local jeweler to do this, but...Does anyone know if Mikimoto will restring any pearls or only Mikimoto pearls? I have Assael Tahitians that I want to restring with diamond rondelles for added length. I emailed them and they never responded.
I have some thoughts if I may...
Since your necklace is Assael, if you get it altered by anyone else, it may void any warranties on your piece. Plus, your piece will no longer be an original Assael piece.
If you want to extend the length, I would suggest contacting Assael and request a custom change. If they will not add rondelles as that is not part of their product line for your strand, then plan B is to add more pearls to your existing necklace.
I mention this because I did this with one of my Mikimoto strands. My alteration was a bit more complex though.
Long story short, I had an 18" strand I never wore because I replaced it with another 18" strand of a larger pearl size.
Hmm... what to do with a strand one no longer needs? Make bracelets!


I sent my old strand to Mikimoto and asked them to make three 7" bracelets. This meant I needed 21" of matching pearls, so I was short 4". Mikimoto matched my pearls and added 4" of pearls. They also added the Mikimoto clasp and M charm.
It worked out great. I love my bracelets.
I just wanted to share this in case it might help in your decision of altering your strand.
You might love extending your pearl necklace with a few more matching pearls vs. adding rondelles which you may get tired of in a few years. For me, there's nothing like a strand of pure unadulterated glowy pearls.
Good luck to you.