Multicolor vintage necklace, material unknown

I don't know the material of this necklace, it was an inheritance and I found it among other jewels, I don't know what its composition is, but it has been left uncared for for many years and has never lost its shine. It may be ruby, but I'm not sure. I have never had an expert test it. If anyone recognizes it, please write to me and tell me if they think it has any value. In any case, I'm going to... superb for everyday use. superior materials and excellent craftsmanship ensure long-lasting durability.