The color of blue fire

Quick answer：

The color of blue fire can vary depending on the temperature and composition of the fire. Generally, blue flames are associated with higher temperatures and can appear as a bright, vibrant blue. However, the specific hue can range from a pale, almost white blue to a deeper, more intense blue. The color is due to the excitation and subsequent de-excitation of electrons in the flame's gas molecules, which emits light at specific wavelengths.