Unique Pendant with Necklace

This is a very unique piece. The shape is almost an elongated diamond. The colour is most accurately reflected in the two last photos. It's a dark charcoal colour. The composition of the pendant isn't known; it isn't heavy, it's smooth with an inlaid design on each side that looks gold in color and could be abstract or not. The necklace cannot be confirmed to be silver but it tarnishes and it's been polished.