The unique combination of chemical stability and physical hardness makes Yellow Sapphire an ideal gemstone for daily wear. Color is the most critical factor when evaluating a Yellow Sapphire. Gemologists assess it using three criteria: The fundamental color. Pure yellow is the ideal. The lightness or darkness of the color. It can range from very pale (light yellow) to very dark. The most valuable stones exhibit a medium to medium-dark tone. The intensity or brightness of the color. This ranges from gray/brownish (dull) to vivid (highly saturated). The highest quality Yellow Sapphires have a vibrant, 'golden-canary' or 'lemon-yellow' color without any brownish or greenish undertones. Yellow Sapphires are mined in several locations worldwide, with certain origins enjoying high prestige. Sapphires are generally cleaner than rubies or emeralds. A 'clean' stone enhances light refraction and value. Yellow Sapphires range from "Eye-Clean" (no inclusions visible to the naked eye) to heavily included. High-quality gems should have minimal visible inclusions.