The clue to knowing from which point of view "The Necklace" by Guy de Maupassant is told can be found in the first sentence of the story.
She was one of those pretty and charming girls born, as though fate had blundered over her, into a family of artisans.
Actually, the first word, she, is enough to let the readers know that the story is told from a third-person point of view. As the story progresses, we learn that the narrator knows what every character in the story thinks, which means the story is told by a third-person omniscient narrator.
What this means, of course, is that we get every character's perspective in the story, and it is the perfect choice for this particular tale. If Mathilde had been our narrator, we would have been made aware of everything she desires and deserves, but we would not have known that she actually has a pretty good life and just wallows in her discontent. We might have believed her dissatisfaction was merited if we had only heard her side of things; instead, we realize that she is just a discontented woman who has overestimated her own value.
If Monsieur Loisel had been our narrator, we would have been fairly clueless about what Mathilde is so upset about; and if Madame Forestier had narrated the story, we would not have had a clue about anything. A limited narrator might have given us the facts but not the feelings.
So, the third-person narrator is the best choice for this story.