How to ID HM LCW  

Start by
searching these threads. I found an LCW in a junk pile and figured out that it was very early H.M. through posts here. If you're REALLY lucky, it won't be H.M. but Evans products. Unreal lucky would be an Eames prototype.

Actually i'm trying to ID a l...
Actually i'm trying to ID a later version by Herman Miller around 1995 -2000, not the vintage one. Is there any tag, writing or number under the chair? Just want to make sure is an authentic from HM.
thx

Yes
It should have label(s).

Sometimes...
they don't have labels, eh woody?
That's when expertise comes in.
He doesn't seem to have that.
Oh well...

.
Not much experience with Eames but you could try counting the laminations in an HM version of a similar age and comparing them, its technically possible for an identical copy to be made but there are often very small differences, try taking some accurate measurments and make a comparison, also check the radius of the edge cut on the seat and back, if I'm not mistaken its very slightly convex.
If you can borrow a vernier gauge (I LOVE the digital ones) you can check the thickness of the parts too.
Another thought, compare things like the style of screw head.
Molded plywood is really a compound material, the glue is as important as the wood, often low quality manufacturers thin the glue with wood flour to extend it, so like all the cheap series 7 copies they delaminate sooner rather than later, I hope for the sake of longevity yours is the HM chair.

Lunch
I would expect a fairly recent production to have the expected labels but it's certainly possible to not have any (e.g. perhaps a factory second).
As always, posting pics would certainly help.

Thanks for the replies. There...
Thanks for the replies. There is a label under.
http://picasaweb.google.com/THECHINH.NGO/LCW?pli=1#

Yes
That is the Eames Herman Miller label for current production.

Labels & Proportions
I've always been able to tell fakes based on the off proportions. The chair is composed of so many organic shapes that it's actually difficult to replicate. Its hard to say exactly what it is - its sort of like looking at a poorly drawn portrait of someone. It just looks off. For example, the photo below.

Why is there a question?...
Why is there a question? Your chair has a label.

just want to make sure...
just want to make sure before buying a second hand chair and I got the picture of the tag afterward, will have it next week ;O)