How do you test for real alexandrite?

To test for real alexandrite, you can use a few key methods. First, observe its color change; genuine alexandrite shifts from green in daylight to red or purplish under incandescent light. Additionally, check the stone's hardness, as it should rank 8.5 on the Mohs scale. Lastly, a refractometer can be used to measure its refractive index, which should fall between 1.74 and 1.76 for authentic alexandrite.