I have just bought this for my Daughter - a 1991 Diamondbike Sorrento - all original, but I've changed the perished tyres and put her fave saddle on. Also changed the chain and put a 11-32 cassette. Its in fantastic condition, just a few small paint chips - even has the original pedals with unmarked christophe straps (kept to one side).
The main tubes and fork are cromo - I think true temper db tubes. It rides really nicely. Paid £50, which I think was ok considering the condition. Also has complete GS 200 group set with double thumb shifters.
Some of the spokes are a bit rusty but rims are excellent.
From these posts. 26 wheels still alive! I'm still a fan of 26 wheels. From personal experience in the city, they are even more preferable to 28 narrow ones. On 26 wheels, the feeling you are a bad guy! :xmas-cool: Great acceleration and maneuverability!