Analysis, part 2 - Collar

Let's just take it from the top. 

Insurrection

A notable characteristic of the DS9/NEM formal jacket was the re-introduction of the mandarin collars seen from The Next Generation's third season forward.

In reality, although the uniforms had evolved considerably since the TNG years - first into the VOY-style uniforms, and then into the DS9/NEM-style - the mandarin collars had never really disappeared for any appreciable length of time. 

Even after The Next Generation concluded its run, the TNG-era uniforms still showed up every now and then:

DS9, 3x22 "Explorers"

DS9, 4x12 "Paradise Lost"

VOY, 2x18 "Death Wish"

They'd also occasionally show up randomly in the background for no apparent reason:

DS9, 6x26 "Tears of the Prophets"

DS9, 6x26 "Tears of the Prophets"

DS9, 5x13 "For the Uniform"

The TNG-era cadet uniforms evolved into the VOY-era cadet uniforms, as worn by Nog and the members of Red Squad during the middle years of Deep Space Nine, which also had the TNG-esque mandarin collars:

DS9, 4x11 "Homefront"

The late TNG-era admiral uniforms also had the TNG-esque mandarin collars, and they were seen for quite a while after The Next Generation went off the air, even after the DS9/NEM uniform "upgrade": 

DS9, 3x2 "The Search"

DS9, 4x11 "Homefront"

DS9, 4x18 "Rules of Engagement"

DS9, 5x10 "Rapture"

DS9, 5x16 "Dr. Bashir, I Presume?"

DS9, 6x1 "A Time to Stand"

VOY, 2x8 "Persistence of Vision"

VOY, 5x4 "In the Flesh"

VOY, 5x24 "Relativity"

Nevertheless, the Starfleet mandarin collars is arguably something that will always be associated with The Next Generation:

In our opinion, incorporating the TNG-era mandarin collars into the DS9/NEM formal uniform to be debuted in the third TNG film, Insurrection, was a brilliant move!

Like in The Next Generation, the upper edges of the mandarin collar were embellished with ⅛" division-colored, braided piping. 

Berry (aka "red") was for command:

Gold was for engineering, security, and operations:

Green was for medical and sciences:

As mentioned previously, the ⅛" division-colored collar piping was braided, as evidenced by this photo of a screen-used DS9/NEM formal jacket, shared by Robert Winthrow on the Starfleet 1701st:

Thanks for sharing, Robert!

Oddly, the collar itself seems to have been sometimes made with the wool elastique of the bib, and other times, it appears to have been made with the wool gabardine of the zipper trim and bottom bib panel. 

The collar in the photo above was clearly made of the same elastique as the bib, as was this one:

However, most of the collars we've examined appear to have been made of wool gabardine:

Insurrection

Also note that, even from a distance, the wool gabardine is easily distinguishable from the elastique of the bib (note how the bottom bib panel, zipper trim, and collar all respond to the photography lighting in the same manner in the auction photos below):

We recommend using wool gabardine for the collar, since we like both the gabardine collar's look and its visual connection to the zipper trim/bib panel (as well as the stylistic consistency with the TNG collars, which were also wool gabardine and obviously a design influence with these jackets), but the choice is yours.

The actual height of the collar varied slightly, probably due to the varying physiques of the wearers; compare Captain Picard's and Admiral Ross' collars to Riker's and especially Bashir's:

Approximately 1" collars

At least 1 1/2" collars

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