Bertoia Diamond 421 manufacturing date discussion  

Hello everyone

I am new to the forum.

I'm trying to sort out some differences between Knoll Bertoia Diamond Chairs.

I noticed that the welding spots that attache the horizontal wires at the front of the base to the vertical ones that form the legs are varying on the Bertoia Diamonds (same with the brackets that hold the base to the frame (solid vs. wire ones)).

So can anybody tell me when they made the design change from the backside of the horizontal wire to the front?

best regards tai.yaki