Couching around a right-angle
Secure by couching a pair of metal threads at equal intervals. At the corner turn the metal threads 90° and work a diagonal stitch separately over each thread.
Continue to couch over the metal thread in pairs by couching at equal intervals.
Structure of stitch
Traditionally used in Goldwork thread embroidery
Various Authors, The Royal School of Needlework Book of Embroidery (2018)