Interesting, its funny you mention this rug, I actually saw this same rug the other day while cruising through google images:
http://www.oriental-rugs.com/antique-tabriz.html Had no idea it was also on ebay for close to 5500 more with a best offer.
Whether or not it's a HJ, I can't say. I haven't ever seen a signed Hadji Jalili rug in person either. As for this rug, it actually appears to be slightly newer to me than turn of the century, maybe as late as 1915, at which time I do not believe people were attributing rugs to this HJ. Why I say this age of 1915, I don't know, could be lack of specific photographs, and the unusually analogous color tone.
The only silk "HJ rugs" I have seen in person have been prayer rugs (as this could be considered), and particularly soft in color such as this however with considerably less brown. The "HJ" rugs I have seen also had bright top colors such as sparse use of light aqua blue. KPSI for the silks does seem to run in this 400 area. Companies such as the Claremont Rug Company in regards to wool rugs, have a very specific style they assign this HJ attribution. Those of which seem to fall into their categorization have this orangish rust color field, Tabriz (true antique 100 years+) and other.
I can appreciate the rug on ebay, as for authenticity I'm not so sure you can ever definitively say with absolute certainty on any of these rugs. With older rugs, it's so important to have some sort of indicator to put things into perspective of what is being presented in images... As a photographer, you can pick and choose what areas to photograph and how to photograph a rug, but the most important areas such as corners, fringe, areas of wear are what really help give clues to what a rug is if not seen in person.
Has your teacher seen this rug on ebay? if so, what does he have to say about it?