Natural diamonds have a distinctive diamond-like luster; for those who frequently handle natural diamonds, the luster alone can reveal whether a diamond is genuine or not.

Natural diamonds come in a wide variety of colors, ranging from colorless to yellow, brown, and even rare and expensive colored diamonds such as pink, blue, and green diamonds. Typically, the color of natural diamonds is not uniform; slight color variations or inclusions can cause differences in shade and intensity. In contrast, the color of diamond imitations tends to be highly uniform and lacks depth and nuance. Moreover, the colors of colored imitation diamonds are often overly vibrant or appear unnatural. Therefore, when selecting a diamond, it’s important to carefully examine whether its color appears natural and exhibits a sense of depth and variation.

Fire refers to the colorful brilliance emitted from the surface of a transparent, colorless, or light-colored faceted natural diamond. The intensity of fire varies among different types of natural diamonds. Genuine natural diamonds exhibit high luster and distinct fluorescence. Moreover, the fire of natural diamonds generally leans toward a bluish-orange hue, appearing dazzling and sharply defined.

Most high-value natural diamonds aren't very large. When shopping for jewelry, if you come across a natural diamond that’s unusually large—especially one claimed to be a rare variety—you should be extra cautious. There’s a strong possibility that it’s either a fake or a substandard stone that has been artificially treated.