My high school colors were navy blue and gray, with white used often as an accent. Graduates of both genders wore navy blue robes and caps with navy and gray tassels. Honor roll graduates wore gray robes and caps with gold tassels. The salutatorians and valedictorian wore white robes and caps with gold tassels.
For my bachelor's degree at Cal State Long Beach, we all wore black caps and gowns with the color of the tassel indicating the subject area of the degree.
On an interesting side note, after getting my B.A. and doing postgraduate studies overseas, I went back and completed an Associates Degree in Fire Protection Technology. At the community college, the graduates wore the typical black cap and gown. However, Fire Technology students have a long-standing, special tradition of wearing
fire helmets instead of caps! Yes, we hung our tassels right from the side of the fire helmets. We got a lot of attention and the professional photographers had a field day taking pictures of our group.
Those who didn't work for a department yet wore the college's fire helmets which are used during classes and training. Those of us who already work for a fire department wore our own helmets. That's why some have different colored helmets in the photo. The guy in the red helmet is a Captain who went back to get his degree! And, BTW, I am first on the left in the top row, yellow helmet.