Check for natural imperfections under magnification
Look for color zoning or uneven color distribution
Examine the stone’s hardness and scratch resistance
Test for fluorescence under UV light
Compare the weight and feel to known ruby standards
Inspect the cut for signs of natural crystal growth
Check for gas bubbles, which may indicate glass
Verify with a refractive index test
Look for inclusions typical of natural rubies
Ask for a gemological certificate from a reputable lab
Have a jeweler or gemologist perform professional testing