With twisted scarlet, the work of a craftsman: This refers to the red yarn used in making the breastpiece (Exo 28.15). It was not made entirely of red, but had red yarn woven into it. We could say “It was woven by an expert [or, artist, craftsman], with decorations of red yarn.” In languages without the passive voice, a possible model is “An artist [or, craftsman] had woven it using red yarn to decorate it.”

With precious stones engraved like signets: See Exo 28.17-21. The priest’s breastplate had on it twelve precious stones, each engraved with the name of one of the twelve tribes of Israel. Signets were precious stones, often mounted on rings, engraved with a name or other design to identify the owner (see the comments on 17.22). Good News Translation “the precious stones with names engraved on them” serves the purpose here quite well. In some languages it will be necessary to make clear what “engraving” involves; for example, “It had precious stones that a skilled worker had written on with a sharp instrument.”

In a setting of gold, the work of a jeweler: Each stone was “mounted in a gold setting” (Good News Translation) or “set in a gold frame.”

For a reminder, in engraved letters, according to the number of the tribes of Israel may be rendered “Each stone with its engraved name represented one of the tribes of Israel.”

An alternative model for this verse is:

• An artist [or, craftsman] had woven the ephod using red yarn to decorate it. There were precious stones on it, set in gold frames by a jeweler, and on each one a skilled worker had written the name of one of the tribes of Israel with a sharp instrument.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on Sirach. (UBS Helps for Translators). New York: UBS, 2008. For this and other handbooks for translators see here.