Gift with purchase Size 9 Vintage High Quality Natural Chalchite Statement Ring

Oval Turquoise look however this size of stone would be a fortune. 3 “ I believe this to be a Chalchite stone set in a 18 karat gold over. Or it could simply be Larimar - don’t know don’t have the tools to identify. All I can say 100 % is that the metal is an alloy. Due to the quality and weight I believe it could be gold overlaid over sterling or brass - it is difficult to say. I don’t know how to use my metal detector! Intricate beautiful design. No stamps to help define.