Larimar marcacite sterling silver necklace

Oh this so beautiful. The chain and clasp is sterling. Marked and tested. The chain is beautiful itself! Then this pendant, I do believe this Larimar. I was told by auctioneer that it was and by what I have researched, I feel confident in stating that. The pendant has marcacite stones around it as well. The pendant is not sterling. I am unsure of the metal and it's not magnetic. There is wear to the back of pendant however the Larimar cabochon is smooth and beautiful. Vintage