Vishuddha is depicted as a silver crescent within a white  circle, with 16 light or pale blue, or turquoise petals ( Accordimg to Wikipedia).

This chakra is the fifth chakra and called the throat chakra (Vishuddha). It relates to  communication, self-expression, identity and creativity (Debbie Creagh).

This chakra relates to the physcal functions of lungs, vocal apparatus, Larynx, Throat, Thyroid  Gland, Para- Thyroid Gland and Lymphatic System. Congestion in this chakra can result in  symptoms such as stammering, laryngitis, swollen glands and ear problems (Lee Wei-Dei).

(Citing Siam Reiki materials)