Arwen's Blood-Red Dress from Lord of the Rings is comprised of two parts: an underdress with two part sleeves, and a velvet overdress/jumper. Don't forget to check out ACS for more information on this costume.

Overdress - The overdress of Arwen's gown is fitted only at the side seams (no darts or princess seams) and made of blue-black silk velvet. The 'straps' that form the neckline are made out of the same brocade as the underdress. There is an invisible zipper in the back (if we go by evidence from her Coronation Gown).

Underdress - The underdress has a scoop neckline and two-part sleeve. We don't know exactly how the underdress is constructed because we've never seen it without the overdress but it is speculated that the red paisley brocade does not extend all the way down. Most likely the brocade acts like a large facing and ends where the overdress begins. The upper sleeves are raglan in shape and this seam is covered by the neckline trim.

Sleeves and Trim - The upper portion of the sleeve is made out of brocade (same as the upper bodice) and ends at the elbow. The lower sleeve are elliptical half-circles and the seam that joins the circle together is on the top part of the arm. The sleeves are made from silk velvet and lined in matching silk fabric. Where the sleeves join, the seam is covered with an overdyed bullion trim. This trim is the same around the scoop neckline.

Linkage:
My Blood-Red Dress
Maggie's Blood-Red Dress - an excellent recreation :)
Yvette's Blood-Red Dress - a beautiful costume