Line-up:

Carlo Degani (vocals, percussion)
Nanni Civitenga (guitar)
Marcello Todaro (guitar)
Giorgio Piazza (bass)
Giorgio Santandrea (drums)

With such an important line-up, it's strange that this group had such a short life. 
Crystals were a sort of supergroup composed by experienced musicians, former members of name bands like http://www.italianprog.com/a_pfm.htm - Premiata Forneria Marconi (Piazza), http://www.italianprog.com/a_banco.htm - Banco del Mutuo Soccorso (Todaro), http://www.italianprog.com/a_rrr.htm - Raccomandata con Ricevuta di Ritorno and http://www.italianprog.com/a_samadhi.htm - Samadhi (Civitenga), http://www.italianprog.com/a_alpha.htm - Alphataurus (Santandrea), and under the guidance of Paolo Tofani ( http://www.italianprog.com/a_area.htm - Area and http://www.italianprog.com/a_frankenstein.htm - Electric Frankenstein ) that composed all of their tracks.They recorded an album that was intended for release on http://www.italianprog.com/l_cramps.htm - Cramps label, but for mysterious reasons it never appeared, and has only been released on CD in the early 90's.
Needless to say, the record shows an excellent musicianship; the lyrics are sung in english, though the album has long instrumental parts; the musical style is closer to english prog even if we can hear some Led Zeppelin influences. A very influential band in the italian rock scene.