This 1980's sterling silver necklace has a 3/4" long slide type pendant that is set with a square blue topaz. This topaz is unusual as it is faceted on the back, but is smooth on the front like a cabochon. The back has a snap closure so it can fit on a strand of pearls of a thick round chain or omega up to 1/4" thick. We put it on a 16" sterling snake chain. Both are marked 925 for sterling, and the slide has a hallmark that looks like, "DAC". The necklace is all in excellent condition with no wear or damage.