This is a stunning necklace. The drop pendant has a circle of Diamonds, with a knife edge bar, another Diamond, a second knife edge bar, and then a beautiful Blue Topaz pendant with Diamonds on the top and bottom. The pendant is hallmarked 18K and 73g O g 053. This could mean that the piece was made in 1953, but that's just a guess. Gram weight is 5.7grms. The chain is hallmarked Italy 14K gold and is 18" long. The pendant is 3" long. All the metal is white gold. The Blue Topaz stone measures 3/4" X 1/2" without the Diamonds. Lots sparkle and life to the stones. There are 19 Diamonds. All The Diamonds are brilliant cuts. Condition is excellent. No replaced or damaged stones or metal. I would date this lovely necklace at c1950's-90's.