This necklace is stamped Silver Mexico which dates it to pre -1948. After that year the eagle mark came into use. Also after 1950 they started using 925 for silver. Looks to be hand made. It is made up of tear drop sterling and green onyx pieces. The green onyx drops are a little larger than the silver ones measuring 3/4" X 5/16". The silver drops measure 5/8" X 3/8" not including the three balls on top of each drop. On the left hand side of the sterling drops are what I thought were dents but every single one has them in the exact same place so this must be part of the design. It has a very simple clasp that is stamped Silver Mexico. Length is 17". Very nice condition with no damage to the onyx pieces. Weight is 46.36 grams.