New Revised Standard Version
The breastpiece shall be bound by its rings to the rings of the ephod with a blue cord, so that it may lie on the decorated band of the ephod, and so that the breastpiece shall not come loose from the ephod.

Contemporary English Version
Then take a blue cord and tie the two lower rings on the breastpiece to those on the vest. This will keep the breastpiece in place.

New American Bible
Violet ribbons shall bind the rings of the breastpiece to the rings of the ephod, so that the breastpiece will stay right above the embroidered belt of the ephod and not swing loose from it.

Douay-Rheims Bible
And may be fastened by the rings thereof unto the rings of the ephod with a violet fillet, that the joining artificially wrought may continue, and the rational and the ephod may not be loosed one from the other.

And may be fastened by the rings thereof unto the rings of the ephod with a violet fillet, that the joining artificially wrought may continue, and the rational and the ephod may not be loosed one from the other.

a lace

Exodus 28:31,37 And thou shalt make the tunic of the ephod all of violet, . . .

Exodus 39:30,31 And they fastened it to the mitre with a violet fillet, as the Lord had commanded Moses. . . .

Numbers 15:38 Speak to the children of Israel, and thou shalt tell them to make to themselves fringes in the corners of their garments, putting in them ribands of blue: