There is a company on the net who supply repro victorian glengarry badges. That looks like one of those. Can't really tell about the glengarry as the photographs aren't really clear enough. I wouldn't be surprised if the label inside bears the size in centimetres or is a Hector Russell logo. Question is does the seller know that it is not genuine? We could of course be wrong and the photo just doesn't do the item justice.
This are comments made by Bugpiper@aol.com who trades a lot on e-bay and is an expert in this field:
"There are tons of restrikes of this badge! This one looks to be deliberately "aged"! Did you notice the black tarnish on the gilding? Silver tarnishes this way not gold plate so, this must have been deliberately added.
As you stated the glenhelmet is wrong! The nylon sweatband is the giveaway. Much too new even if in shite condition."
I've seen pictures of the 1800's infantry sealed pattern glengarry that was sent out to manufacturers at the time. The band on it was leather.
I believe though that the BW glengarry always had a 'wide' ribbon band, and as far as I can tell, has never used a ribbon cockade behind the badge.
(about time the Infantry went back to the glengarry )
I suspect the seller just doesn't know, looking at what he's purchased in the past. He hasn't sold much to see a pattern there though.
The "patina" on the badge certainly looks "applied", and bugpiper is correct about gold/gilt oxidising.