Question about a silver ring with a stone

Hello! My question is is it possible to have a diamond on a silver ring? I own this silver ring with a baguette cut stone. Ring is marked J*A 925. On the diamond tester set to three or four, it fills the scale one square before the end! (I have a lot of jewelry with stones including gold, but no other stone does this)! I guess even and if it's a diamond it's synthetic...?! How do I determine how much it costs?

 

Diamonds are sometimes set in silver, but your stone is not a diamond.
At 9 on the Mohs scale it could be a sapphire (leucosapphire), either natural or synthetic. But it is best to have it tested.

 

I have tested the stone with Diamond selector 2, it determines the thermal conductivity of the stone! Basically, the instructions say that any crossing of the border and entry into the red sector, regardless of the squares, only happens when a diamond is present! If anyone knows how far to put the selector in the test - please help, the stone is approximately 8 x 4 mm in size.

 

Do you have a diamond in a different piece of jewelry? What I do with those testers is test something I know for sure is a diamond, get a positive result in the tester and turn the selector down to a point just where it tests positive. Do a 2nd test, be sure the genuine diamond is testing, then test the piece in question.

 

Diamonds usually test as diamond no matter where you have the tester set. I've never seen a totally clear large-ish size diamond set in a modern silver setting. Really old ones are another story. They're more often small and off-color. I'd be more in Any's camp and thinking lab sapphire. White sapphire that size would be more likely to be set in gold too.

 

I have the "Diamond tester II, same as the OP's. These testers are cheaply made machines and I don't think all are perfectly calibrated. Mine was $12 on Ebay with free shipping. At least for the one I purchased, I need to set the tester at 5-6 or the diamond doesn't register. (Note: If you set the machine too high you can get false positives.) So I always do the experiment with a genuine diamond first, set it just to the point where it registers, check it twice and then test the item in question. I haven't had it fail me.

I'd be curious if other people can just set their inexpensive testers to zero and have it work. Maybe it's time for a new machine.

Either way, I think comparing the machines reaction to a real diamond first is good practice.