If it's an actual BMW part...it should have either the full 11 digit BMW part nbr...or the shortened 7 digit BMW part nbr (the last 7 digts of the 11) somewhere on it...and usually has the "
BMW" acronym or the Roundel embossed on it somewhere.
If you can find the 7 or 11 digit part nbr...you can easily find it by just inputting that in the part nbr search on one of the online part database sites like
www.realoem.com or
www.bmwfans.info or
www.bimmercat.com