Part of the Pearl Purl "family".
Wire Check is version of Bright Check Purl (please link through to read about that wonderful thread) only it is less shinny and more subdued. The Wire Check is just as fragile and fine a thread as the Bright Check. It is not used as often as it's sister thread but it is very useful in creating contrast or sense of depth in the work. Note: I will update this post with a picture of the Bright Check and Wire Check worked on MR's Fleur as soon as I return to that piece.
Today, we have lots of color choices beyond the traditional Gold and Silver. Below is a picture of four different some of the colors within my stash.
Please refer to Bright Check Purl.