Vintage Black Beaded Pendant Necklace

Offered for Sale is this Vintage Black Beaded Pendant Necklace interceded by pearl/faux pearls beads.  The Necklace has an oval shaped polished pendant with striations which can be seen in light at certain angles, images included.  I do not know whether this is Jet, Onyx or something else so it is being sold as "Black Beaded".  It does have quite a bit of weight to it.  Measures approx. 55cms in length including pendant.