What is it? no idea please help

It is not plastic I Checked with a hot needle. Thank you for your answers!

 

It appears to be a ball of onyx in a gold mount. Is there a stamp on the suspension ring?

 

No stamp, thank you so much!

 

How big is it? Cold to the touch or warm? Can you see through it if you hold it to the light?

 

Please don't use hot needles. Even if it is plastic, some of the older plastics are highly collectible. I sold a lot of it and made good money. I occasionally got lots where a couple of pieces that would have sold well were ruined by holes from needles. There are so many ways to test items without trashing them. I don't know why people don't realize that plastic can be valuable.

 

Size would be helpful.
Looks like a glass marble to me.

 

Same here. Black glass. I've never seen that mount in any precious metal, and rarely even plated with real gold.