The Alfred Jewel shows a man with a V-necked tunic with sleeves going down to the elbow. Hence we can guess that this is based on the style of male clothes at the time the Jewel was made (the 9th century).
The colour of tunic the man is wearing may also reveal something about the colours Anglo-Saxons wore.
The man on the jewel is also wearing a belt and we can just about see his hairstyle.