Blue gem-red fluorecence question

[ioannis]

Dear sir or maddame..
As i told in many other issues i own pawnshop and usually intresting items come in to shop..today one intresting item arrived but unfortunately i dont know what is it..it has a normal light blue color as you can see in the photo but under uv light it emits red fluorecence its weight is 2.03 carats and dimensions is 0,88x0,55 cm what gem it could be and does red fluorecence means synthetic creation?

 

[tourma-guy]

Synthetic blue spinel will fluoresce red under UV. That's a possibility. Sapphire can also have fluorescence, but its usually on the weak side from what I understand.

 

[lilmosun]

I wouldn't try to identify the stone but fwiw my unheated purple-blue sapphire definitely fluoresces under a UV light...it's not as light as the stone pictured.

 

[chrono]

It could be synthetic but fluorescence alone isn't a definitive test. The result is usually considered together with the RI number to narrow down the possibilities. Any way to test the SG?