Aside from his purple/green plaid trousers, perhaps the most iconic component of the Joker’s costume was his trademark purple Victorian tailcoat (also called a “dress coat”).
(The leftmost gentleman pictured is from R.I. Davis’ Men’s Garments 1830-1900, second from left is from Jason MacLochlainn’s The Victorian Tailor, and the gentlemen pictured in the rightmost (non-Joker) image are from Frederick T. Croonburg’s The Blue Book of Men’s Tailoring.)
For those of you who are not familiar with Victorian jackets and coats, tailcoats are in the same family as frock coats and morning coats, with the primary differences being in the cut and construction of the coat’s “skirt” (or “tails,” in this case).
A frock coat has a full skirt all the way to the center front (see Doctor Who‘s 11th Doctor, lower left), a morning coat has a rounded lower front (see Sherlock, lower middle), and a tailcoat has the majority of the skirt’s front cut away, leaving only the “tails” (see Joker, lower right).
Here are some excellent close-up photos of the tailcoat as part of two screen-used Joker costume displays, in which the fabric weave (and some construction details) are observable.
Special thanks again to Paul Wares for these!
The four front buttons were shank buttons, covered with self-fabric.
Behind the buttons and front edge of the “tail” was a fitting dart.
Although Victorian tailcoats often had silk-faced lapels and modern tailcoats often have satin lapel facings, the Joker’s were simply the same purple (self) fabric as the remainder of the coat body.
Also, as mentioned previously, his tailcoat’s collar and peak lapels were very similar in design to the purple suit that he (Jack Napier) wore before his transformation into the Joker: wide, with rounded lapel tips.
On his tailcoat’s left lapel was a small buttonhole.
The buttonhole was more obvious toward the end of the movie, once dust was caked around and inside of it.
The left lapel’s buttonhole was usually only decorative, but he did make occasional use of it – once for his acid-spewing flower:
And during a brief scene, he wore a lapel pin that appeared to be stylistically similar (perhaps identical) to the playing card cuff links he wore on his shirts’ sleeve cuffs.
Also on the left front was a small pocket, which the Joker used to display his various handkerchiefs.
As you can see in this costume display photo (again provided by Paul Wares), the outer/side edges of the breast pocket were fastened down with topstitching.
Like Jack Napier’s purple suit, the Joker’s tailcoat also had the Victorian-style shoulder seam.
The Joker’s tailcoat also had the ubiquitous Victorian princess seams in the back.
In keeping with Victorian convention, there were two shank buttons (again, apparently covered in self fabric) in the back where the princess seams met the waist seam, below which there was a small pleat on each side.
At the center back was the typical Victorian-style vent.
The sleeves of the Joker’s tailcoat were the typical two-piece sleeves often seen on Victorian and men’s tailored garments, and the top of the back sleeve seams aligned nicely with the upper edge of the coat body’s back princess seams.
The bottom of the tailcoat’s sleeves were vented and had four closely-spaced small shank buttons (again, seemingly covered with the purple self-fabric).
Unsurprisingly, the Joker’s tailcoat was lined with purple – probably the same purple lining as the back of the waistcoat.
We also know that there was at least one interior pocket on the left front of the tailcoat …
