I noticed it, too (like how could you miss a 1977 new,old stock S1 guitar or bass?!?). Amaranth is purpleheart, right? If so, the top and back look like they have mellowed exquisitely. The zebrawood laminate is very unique and very cool. I'd love to do something like that with a bass, if I build another.
Looking at this guitar seems strange. It has little appointments (i.e. chrome tuners) that remind you it's a vintage Alembic - but you usually see those things on instruments that show their age!! This one looks brand new, except for the mellowing of the wood color. I guess that's what they looked like...
Cool.
Bill