Identifying Your Emerald Necklace: Carat, Metal & Stone Identification

Question
On the back of the mounting... there is a '1/20' ....is that the  carat of the stone?  Also the mounting has
'12k GF' on back.  Is there a symbol/mark telling me what stone.... emerald, sapphire, diamond etc ?  or is that symbol/mark of the maker .....like a "T&K" combined together to make one symbol/mark.  The stone seems to be an emerald (medium dark green) but with a hint of blue in it...maybe a sapphire ???   thank you for you help...Brent

Answer
As it states in my profile I can't help much with markings, but I would think that 12k means 12 karat gold. I can't venture to guess at any of the other markings. A jeweler can use marking for several reasons and none of them are standard. They can mean something to him for inventory purposes, it can be a type of signature, or they can have some significance to the person they were made for. There are a lot of possibilities. I have not seen stamps used for stone types, at least not amongst the jewelers I deal with.

The stone sounds like an emerald based on the description of the color. Some emeralds from Muzo and Chivor and a few other mines cans sometimes have a blue hue and its mostly regarded as a good characteristic. Not many other stones can be confused with that color description so I'd probably rule out a sapphire.