You have already asked a similar question. As mentioned, this is completely normal â when you put your hands in cold water, the blood vessels near the skin react to the temperature change and become more visible, appearing blue or greenish. This goes away once your hands warm up, as you have noticed. There is no deficiency or disease causing this.
Next Steps
No investigation is needed for this, as it is a normal physiological response to cold. However, if you ever notice your fingers turning completely white or blue and staying that way even without cold exposure, or if you feel numbness, please get evaluated. Feel free to consult me directly on Practo for a detailed evaluation.