Exodus 39:29-31 New King James Version (NKJV)
29 and a sash of fine woven linen with blue, purple, and scarlet thread, made by a weaver, as the Lord had commanded Moses.
30 Then they made the plate of the holy crown of pure gold, and wrote on it an inscription like the engraving of a signet:
HOLINESS TO THE LORD.
31 And they tied to it a blue cord, to fasten it above on the turban, as the Lord had commanded Moses.