Hi Ginger,
It is incredibly difficult to analyze a stone with images only. The observations you listed are good data points but without some standard gemology diagnostics, narrowing down the possible species is challenging.
You mentioned the red stone did not display internal glow. Does that imply you placed the stone under a UV lamp?
The stone seems opaque. I personally haven’t seen opaqe lab-grown spinel. Typically they are very transparent. I believe glass-fill treatment is done to stabilize and improve the clarity of a stone
Ruby glass filled or natural. This topic has some good links to review.
Without some diagnostic data its difficult to determine.
‐-------------
Post Correction
Apologies! My original reply was sent from my mobile. The last image in your post was actually of the red stone and not the black stone. Didn’t make that connection until reviewing the post on an actual monitor vs phone screen.
For the black stone. If it is indeed, Jet, the SG should be around 1.25 -1.33 and an RI will show a shadow line around 1.66.
Do you see any light coming through the stone?
You could do a salt-water test similar to what is used to filter out most plastics from natural amber. Here is a forun topic on that:
Don’t recommend any destructive test like a hot point test or hardness probe.
‐-------------
Can you un-mount the red stone to do some tests like SG and RI?
Cheers!