Citrine stone, partially faceted and partially polished, approximately 1" x 3/4". The color is an amber yellow, and the faceted areas are quite refractive. There are some tiny irregularities on the facets, seen only under magnification. Citrine is often heat treated to enhance the color, I cannot tell for certain whether this has been done.
It is marked 925 for sterling silver on the bale and again on the clasp of the 18" chain. It is in excellent condition with little or no signs of wear. The former owner stored this in a jewelry pouch, so the sterling is untarnished.