This site sells numerous coloured cords in various sizes, though not necessarily designed for roman blinds, you may find them suitable.
Some cords has may be loosely woven and may stretch if used for roman blinds - Ask for a sample.
Colly Brooks also supply coloured cords
Collybrooks
Cord Site
my.decozo
Some cords has may be loosely woven and may stretch if used for roman blinds - Ask for a sample.
Colly Brooks also supply coloured cords
Collybrooks
Cord Site
my.decozo