Check for fog: breathe on the diamond and see if the fog clears quickly
Use the water test: drop the stone into a glass of water and see if it sinks
Look at the sparkle: real diamonds reflect white light and colorful flashes
Read through it: place the stone over printed text and see if you can read through it
Check for scratches: a real diamond can scratch glass
Inspect with a magnifying glass: look for tiny imperfections or inclusions
Test the setting: real diamonds are often set in high-quality metal like gold or platinum
Use a UV light: some diamonds glow blue under ultraviolet light
Compare weight and feel: diamonds are denser than many lookalikes
Try a thermal test: a real diamond disperses heat very quickly
Look for sharp edges: real diamonds usually have crisp facet edges
Check for uniformity: fake stones often look too perfect or overly flawless
Use a diamond tester if available
Have a jeweler confirm it for certainty