Examine a sapphire under strong light with a jeweler's loupe to look for scratches, bubbles and light reflections that indicate the stone's origins. If in doubt, a certified gemologist can give a definitive answer as to whether or not the stone is genuine.
A sapphire can have greater value if it is large, deeply colored and clear. False stones attempt to mimic these qualities.
Step 1: Use a jeweler's loupe
This is a small magnifying glass that allows the user to spot small imperfections in the stone.
Step 2: Look at the stone under bright light
Bright light helps those examining the stone to see telltale signs that a stone is fake. It also reflects more light. Genuine sapphires should always reflect the same color as the stone rather than different colors.
Step 3: Look for scratches
Diamonds are the only stones harder than sapphires, so there should never be a scratch on a genuine sapphire.
Step 4: Look for bubbles
Genuine sapphires do not have bubbles inside the stone, but glass replicas can. If there are bubbles present, the stone is not genuine.
Step 5: Talk to a gem expert
If examining a purported sapphire does not yield enough clues, a certified gem expert can clear the issue up once and for all.