How can I tell the difference between Rough Diamonds and other Gems?

Question

I have done the "scratch test" and other tests but still have a huge ammount of stones which I have "deemed" to be diamond, but theres still that feeling it could be sapphires or yellow garnets...

Answer 1

Well, if you had a spectroscope that would tell you...

But wait, garnet is significantly softer than even sapphire let alone diamond, so you could eliminate those at least.

Diamond vs Sapphire is tougher. Spectroscope I guess...