I am currently the Digital Coach for the City of London and the West, within the London and Midlands Region. My role in a nutshell is to coach our leaders on sustainable banking whilst making the lives our of customers easier.
(There is also genuine color-change sapphire which mimics alexandrite, as well as color-change garnet that can be a real fooler.). The first thing to do is check the refractive index of the stone, since each material has unique optical properties.
Below are pictures of a Garnet. This is one of the most widely available color changing gemstones on the market today. This is the standard for defining color change in color changing gemstones: it is the difference between what you see in natural, (I.E. sunlight,) and any other light source. The definition of color changing gemstones needed to be modified again when fluorescent lights were added to the equation.