The fakes all seem to have a smaller die, and most have square bond wire pads where genuine Cree LEDs have round pads.
This is maybe a better picture it is from Convoy S2+.
You think this 2 wires that are touching the LED ?
The 2 bond wires on the side of the LED die is the most notable indication for most of the fake ones, the real Cree ones have the round pads like the pic above.
Yep, understand.
Does anyone here find a way how to determine differences from genuine Cree led series like XM-L2 ?
U2, U3 and U4 for example how to know what is about or it is not possible ?
i’m not sure how to tell that part of the LED designation.
Update! I figured out how to post.
Real or fake cree?!
I have a picture I would like to post, but for goodness sakes I can’t figure out how to add a picture. I’m in my late 30’s, not ancient lol. Can anyone help? I don’t have a “url” to post a picture. Why can’t I simply copy and paste?! Lol
I'm 61 and have posted 100's, maybe 1000's of pics here, of course I've been programming computers for like 40+ years 
I use "Advanced Post Editor", then click on the top most "Insert", choose Insert/Edit Image. Then in the Source field, you need to enter a URL directly to a picture. Here's one to use as an example:
https://oi1054.photobucket.com/albums/s496/TomE2012/Custom%20Mods/P1030101_zpsac2bbr10.jpg
In the inserted image, it will look like this:
I reduced the size from 1024x768 to 300x225 in the "Dimension" entry. The tricky part is to find a hosting service/server that you can get url links from. I use PhotoBucket in a paid for mode though. Lot of people here use imgur.com, but I find it somewhat hard to use.
Thank you!
What you think? Real or Fake Cree?
I am unsure what those are, they look like a cross between a XTE Cree and the odd-ball LEDs found in some Skyray King clones i seen, as most of the cheaper random-branded lights have been using the knock-off Latticebright ( and now other random unknown LEDs, its difficult to tell when it comes to buying unknown brand lights.
Ok. Your meaning Cree XTE? It does look like the picture in that thread. I’m about to buy 60 of these and I just want to make sure they are the real deal. So it can be a Cree and not say Cree?
So you think for sure not Cree? Thanks for your reply!
The genuine XTE: > https://www.cree.com/led-components/products/xlamp-leds-discrete/xlamp-xt-e-white
Tricky business! Hard to really know
I zoomed in on your pic and I don’t see the dot that’s in one corner of the XTE’s.
Thank you for your observation. I’m an amateur at identifying fakes. I’m about to drop a couple thousand dollars on lights and don’t want to be taken for a fool.
Very Helpfull thread,thanks!
have some old XM-L same package as original and bond wires
but die size a bit smaller than the authentic
will post photos soon
Anyone knows if this is a fake XM-L2 u3 or not? Got this from Aliexpress.
Thanks
It looks like the real thing to me but the bin could be anything. But you never know just how cleaver they can be.
This might help a little.