The Tenth Foundation Stone of the Heavenly Jerusalem: Chrysoprase
"The chrysoprase has a mixture of green and gold, deriving from it a certain purple gleam, with specks of gold interspersed. It is found in India; and it signifies, that they who well deserve the verdure of the eternal country by the brightness of perfect love, make it manifest also to others by the purple light of their own martyrdom. For since they follow the example of the Lord manifest in the flesh, in that they despise the present life, and prefer eternal glory, they shew even now, as if in India, that is, near the rising of the sun, the brightness of their own deserts. And because they desire to “shine as the sun in the kingdom of the Father,” and there to reign with their King with Whom they now suffer, and wait for this, they are rightly put in the tenth place. For by the denarius, with which the dressers of the Lord’s vineyard are rewarded, is represented the image of the eternal King, which is to be received when, as it could not be in the ninth degree, through the perfect love of God and of our neighbour, the decalogue will in all points be fulfilled."
["The Explanation Of The Apocalypse," by St. Bede the Venerable, 7th Century Doctor Universalis]