Vintage 925 sterling silver necklace with large blue teardrop pendant

Vintage sterling silver necklace. Both the pendant and the chain are stamped 925. The pendant is large, teardrop shaped, with faceted deep blue stone that looks like a sapphire, but could be lab created. The stone is slightly larger than its frame and is coming out by about 1 mm on the back, as pictured. The chain is delicate looking, 17" long. The pendant is 1.75" long (with bail) Both are in very good condition.