Gem identification techniques involve various methods to determine the authenticity and characteristics of gemstones. Common techniques include visual inspection, where gemologists examine color, clarity, and cut, and the use of tools like a loupe or microscope for detailed analysis. Other methods include refractive index testing, which measures how light bends through a gem, and spectroscopy, which analyzes the light spectrum emitted by a stone. These techniques help distinguish between natural and synthetic gems, ensuring accurate identification and valuation.