As Thermage uses radiofrequency, and not a laser that seeks a target, chromophore, the skin's color doesn't affect the absorption of energy of the Thermage device. However, it is important to undergo such treatment by an experienced, hopefully, board-certified dermatologist or plastic surgeon as there is a rare chance of an arc of energy that could cause a thermal skin reaction and should that occur in skin of color, there is a greater chance of development of post inflammatory hyperpigmentation (dark spots). So technique is extremely important. In my practice I perform all treatments on my patients, and ensure that there is adequate fluid on the skin and the right pressure of the handpiece on the treated site.The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice. The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs.