Alexandrite is one of the rarest gemstones in nature - a color-change chrysoberyl that appears green in daylight and red or purple under incandescent light. Lab-created alexandrite delivers the same color-change optical effect through the same corundum-like chemistry at a fraction of natural alexandrite's price. At 0.73 carats oval in 18K yellow gold over sterling silver, this pendant captures the alexandrite phenomenon in a wearable, elegant form: the stone will genuinely look different under different light sources, making it a gem with conversation built in. The Cancer zodiac designation makes this a compelling and distinctive birthstone pendant for June-July birthdays. A color-change stone is one of the most compelling jewelry experiences available.