Featured Art Deco gold ring yellow stone or diamond

Here is another piece I got today, has some writing but hard to make out the whole thing, maybe it was resized at one point. No gold karat markings anywhere but it is at least 10k, 18k acid fades the scratch a little so not sure.
Anyone know what kind of stone this might be ? Needs a god cleaning.

Thank You

Billy D.

 

One less than expert opinion on the stone: glass or amethyst treated to look like citrine. It is not uncommon to find older 10K rings, from when gold was not so phenomenally expensive, set with glass stones.

 

Okay, Thanks again Bronwen..

 

Good thinking Bronwen. My first reaction was citrine, but glass is equally feasible.

 

The stone could be almost any number of types quartz,topaz,beryl,sapphire,etc.

 

Think we can plausibly rule out diamond & fancy sapphire on grounds of size alone; can't imagine such a stone going about incognito. Stone could probably use a cleaning, but think, even after, it would not have enough flash for chrysoberyl or topaz. Natural citrine actually rather rare & tends to be pale. Wrong shade for yellow tourmaline. Not much left to choose from among stones commonly used in jewelry.

 

It's probably a "three bears stone",it needs to be cleaned and a well lighted photo.Not having "enough" flash is a matter of geometry and not the type of stone.

 

I just cleaned it, here are some more pics.

 

Nice ring, Billy.
About the stone. There don't seem to be any bubbles, so probably not glass.
No pleochroism (rules out topaz and some others). Shell-like fractures. My guess is citrine.

Billy, do you know anyone with a diamond tester? It tests hardness on the Mohs scale, so other gemstones as well.

The mark is intriguing, it looks like an old Middle Eastern mark. Not North African, those are in cartouches.
I have some info on Middle Eastern gold marks, but can't find this one. Could be a maker's mark.
If the ring was made in the Middle East, the stone is not treated. They didn't use treated amethysts there in those days.