Bertoia Bird & Diamond Chair's... Real or Repro's?  

double wire edge?
Is the wire around the edge single or double? If memory serves, Bertoia chairs have single, Eames have double.
Repro Bertoia have double. Not 100% sure...

Bird is a knockoff for sure.
Can't tell from the photos of the Diamond, but I'd guess it's the same.

fastfwd can you tell me why?
I am not doubting you, in fact that was my instinct as well, but can you tell me what it was that made you come to that decision? I am just trying to educate myself for future.
Thanks.

Hi there,
I agree with...
Hi there,
I agree with Fastfwd.
I am no expert, but this is what my Bird looks like - you can tell the difference in construction.

Too me it looks like the...
Too me it looks like the metal bracket at the back, in the last picture, was added later. Just compare the huge welds to the other welds on the base. Looks like a home repair to me... maybe the original shock mounts failed and someone decided to get crafty?

It looks like the original wide base of the bird chair was replaced by a more narrow base of a diamond chair.
The chairs definitely look old and copying Bertoia chairs is a fairly recent phenomenon so my guess is that they are original chairs but with a home repair on the bird chair.

rubybubble
I guess I was too hasty. It hadn't occurred to me that the chair might be a marriage of parts, but now that alexandersforum and vintagestique have suggested it, I must say I agree.
To your questions:
1. I can't tell the age from the photos, but for these chairs, age doesn't really affect the value directly. All that really matters is condition: The welds are often broken, and the foam is petrified on all older chairs.
2. Broken welds must be repaired; if you don't fix them, more stress will be placed on the nearby welds and soon they'll break, too. Eventually, someone will sit in the chair and the entire seat will just tear out of the frame.
Clean welds made by someone who knows what he's doing -- hint: if he wants to use a stick welder, he doesn't know what he's doing -- will not hurt the value of the chair. Be aware, however, that the Bird chair is already highly devalued because of its non-rocking narrow replacement base, so if originality and value are important, repairing that one might be more trouble than it's worth.
3. Covers are available from Knoll, of course, but prices for the Bird range from around $800 to around $1500. The only source for custom Bird covers that I know is David Arevalo, at Comfort Upholstery in Chicago. He was making them a few years ago and probably still does. I haven't seen them, but he did a good job on my Cone chairs so I would expect the covers to also be done well.

double wire
Is right that that repro Bertoia have double wire edge around the chair? I thought that original chairs had the double wire edge. Someone knows it?