Red is generally the colour representing guilt , e.g.o n the day of Atonment ( Yom Kippur)in the Holy Temple the red string would turn to snow white to show that the nation was forgiven. I don't know if you want to go there. On the other hand, the Henrew word for red is Adom, and on the High Priest's breast plate there was a red stone called Odem (in hebrew the letters are the same because vowelisation is different) which is a Ruby in English. It represented the tribe of Reuben. Can that help?