The most typical birthmark meeting that description is a strawberry hemangioma.
A soft raised dark reddish-purple birthmark is typically a type of vascular birthmark known as a hemangioma. These marks are benign and result from an abnormal proliferation of blood vessels in the skin. They can appear at birth or develop shortly thereafter and may change in size and color over time. While most hemangiomas do not require treatment, some may need medical attention if they cause complications or cosmetic concerns.
Birthmarks that contain blood vessels are called superficial hemangiomas. These vary from the "strawberry angiomas" to the capillary distention known as "port wine stains". Some hemiangiomas are caused by small skin tumors and some are simple lesions. These marks differ from "moles" (nevi) which are not primarily vascular.
A gas suitable for a reddish purple advertising light could be a mixture of neon and helium. Neon produces a reddish glow, while helium can help enhance the intensity and stabilize the color of the light. This combination can create the desired reddish purple hue for the advertising light.
violet
reddish purple
They are large reddish purple spots
He is well built and has an ugly purple birthmark on his neck.
reddish purple
Your question will have to be more specific. In terms of the actual color, there is no medical terminology. In our hospital, any purple coloration is described as purple. For a specific medical condition, the color purple could indicate a discoloration, which would imply a more technical term pertaining to the ailment.
Rust or marroon, which is more purple then red
yes
It is a light blue