0ur Review: :Garnet is one of the few gemstones that can exhibit a natural color change phenomenon, and the display is truly enchanting. This 5x4mm color-change garnet comes from Tanzania and has a weight of .38 carat. Beautifully faceted, it changes from a teal blue color when viewed in daylight to a deep raspberry red when viewed with incandescent light. The change is caused by a difference in the way various types of light affect the atomic ...