lapidary, whereas a person who cuts and polishes gems is named a gemcutter or a lapidary (sometimes lapidarist). Shade change is an optical characteristic of a small number of gems. A color-change gemstone's appearance varies when seen in different lighting environments due to shifting wavelengths. Photochromism (or photochroism) is the technical time period for colour-change. The very best-known color-change gemstone is alexandrite. When viewed in sunlight, this phenomenal number of chrysoberyl seems greenish. Noticed underneath incandescent mild, the gemstone appears reddish.