If I recall correctly, thick and iridised scavo on black glass was introduced as a colourway c.1983. Pretty sure it's an Antonio Da Ros design - although it's hard to say for certain as Cenedese reproduced quite a few old Seguso Vetri d'Arte designs (including quite a lot of scavo) in their own colours after they acquired SVdA's catalogue in the 1990s.
And from what I understand, the full 'Gino Cenedese' signature (Gino died in 1973, so the signature doesn't refer to the designer, just the company that survived him) was used on items destined for galleries, exhibitions, etc., occasionally twinned with the designer's initials (A.D.R. for Antonio Da Ros, for example).