What does 4K PAT FL-C mean in a ring?

[rsilvers]

My Grandmother's ring says "4K PAT FL-C" inside. My mother said it is Platinum. I am not so sure. Does that marking mean anything? It is only about 15 years old because it was an anniversary present. It has a 0.8 carat center stone that to me is at best a J-SI2 and maybe worse.

 

[Garry H (Cut Nut)]

No idea, sorry.
Plat is a standard stamp for platinum. There is no C color, so FL can not mean Flawless.

 

[Tarams]

Just like MA is Michael Anthony, I would think it's the designers trademark, or the caster/setters signature or mark.
Unless the 4k part was at one time 14k and part of it wore off, I can't make any sense of it either. Sorry!

 

[rsilvers]

It is white in color. Looks like it could be Platinum. The 4K was never 14K because it is very cleanly stamped and I used a microscope. I guess I could weigh it. The stone seems to be a .80 center with 4 small ones that most likely bring it up to a 1.0 tcw.

 

[Tarams]

Then it could be a european stamp.

 

[rsilvers]

How does one test for Platinum? Or is is just obvious to any jeweler?

 

[Garry H (Cut Nut)]

With acids and it feels heavier (relying on experiance).