identification of antique chandelier aquamarine earrings

[diamonddemon]

I would like to know approximately what era do these belong to. They are yellow gold (18k) with an overlay of silver? platinum?
I tested the yellow part to be 18k , but acid testing on the silver part survived the 14k acid, but I failed to 18k acid and platinum acid. Could it be silver overlay?

The stones are aquamarines, there is also a small rose cut diamond on each. The only marking I can make out is 18ct.

Thanks