Silk shantung is a plain-weave silk fabric that’s often confused with silk dupioni. The name derives from the Shandong area of China.
Both fabrics feature ‘slubs’ which are natural irregularities in the silk thread from the silkworms’ cocoons. Shantung is smoother than dupioni, with fewer slubs in the weave. From more than a few feet away, it looks merely textured, whereas the slubs in dupioni are quite visible.
Shantung can be found in all colors of the rainbow, with printed and woven patterns and embroidered motifs. It ranges from $15/yd to $100/yd for the fancy decorator / high-fashion yardage.
Because it’s smoother, it looks a little more luxurious than dupioni and it’s a popular choice for formal wear. It’s definitely a special-occasion fabric, suitable for wealthy / high-status characters.
Like dupioni, you can find look-alike fabric made with various artificial yarns for a fraction of the cost – as little as $5/yd for very lightweight faux-shantung. Artificial fibers are warmer to wear than silk, but cheaper and it might be easier to care for, depending on its composition – it’s usually acetate, polyester, or rayon.
Beware the seller offering silk shantung at a price that’s too good to be true. Check the descriptive text for weasel words like silky or silk-like. Or the text might leave the word silk out entirely and count on the buyer making a (wrong) assumption. If you have your doubts about a fabric’s composition, get a swatch and perform a burn test.
Silk shantung should go to a dry cleaner or, if you can’t trust them with your costume, hand-wash it in cool water and lay it flat to dry. No dryer!
It frays easily, so check out how to handle fray-happy fabrics before you start cutting.
PS, my reference books have just reminded me that there is a very similar fabric from India called tussore and sometimes one may be called by the other’s name.

Polyester shantung. Very hard to tell the difference between polyester and silk if a picture is all you have to go on. Source: housefabric.com