Textures should vary, which is why a conventional silk necktie is better paired with a linen pocket square than an equally smooth silk. There are exceptions however. Conventional silk also contrasts well with silk Shantung, silk grenadine and silk knits, none of which have the same sheen.
In the photo, for example, Rubinacci's Arcimboldo nero pocket square is displayed with the black border hidden and the blazer-compatible colors visible. A man would probably not wear gold buttons and a silk square to his office but they make a great change of pace for a dinner engagement.