Superb sterling and stone teardrop pendant

I am not sure of the stone in this pendant - tourmaline, fluorite, zoisite? - but it the colours are very rich*. The silver is nicely etched around the frame. The pendant hangs about 1-1/2 inches, including the round bail, which is stamped 925. The pendant is in great condition, though there was a separate piece of silver sodered onto one piece of the frame (see last picture), which is slightly visible, and another at the top of the back, which is not visible from the front.(p) Thanks to Catriona who has indicated that the stone is natural ruby deposited in zoisite!