'Scarlet,' as in Genesis 38:28, signifies spiritual good.

In Isaiah 1:18, this signifies truth derived from good, or truth from a celestial origin, such as is the truth of the Word in its literal and natural sense

'Scarlet,' in Revelation 17:3, signifies truth from a heavenly origin, such as is the truth of the Word in the sense of the letter or natural sense, which is meant by what is holy in it. 

(References: Apocalypse Explained 67)

114. The truth of faith was also meant and represented in the Word precious stones, for example, those in the breast plate of judgement, and upon the shoulder-pieces of Aaron's ephod. in the breastplate, the gold, blue, purple, double-dyed scarlet, and fine-twined linen represented matters of love, while the precious stones represented matters of faith deriving from love, as did the two stones of remembrance on the shoulder-pieces of the ephod which were made from shoham encompassed with settings of gold, Exodus 28:9-22. The same point, that the truth of faith is meant and represented by precious stones, is plainly stated in Ezekiel when the subject is the person who possesses the heavenly riches of wisdom and intelligence,

Full of wisdom and perfect in beauty, you were in Eden, the garden of God. Every precious stone was your covering ruby, topaz, diamond, tarshish, shoham, and jasper, sapphire, chrysoprase, and emerald. And gold, the work of your drums and of your pipes, was within you. On the day that you were created they were prepared. You were perfect in your ways from the day you were created. Ezekiel 28:12-13, 15.

Anyone may see that celestial and spiritual things of faith, and not just stones, are meant. Indeed each stone represented a particular essential element of faith.