This text comes from Mediaeval Hymns and Sequences, edited by John Mason Neale, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
Ye of the heavenly country, sing
The praise and honour of your King,
The raiser to its glorious height
Of that celestial City bright,
In whose fair building stand displayed
The gems for twelve foundations laid.
The deep green hue of Jasper saith
How flourishing the estate of faith
Which, in them all that perfect be
Shall never wither utterly,
In whose firm keeping safe we fight
With Satan's wile and Satan's might.
The azure light of Sapphire stone
Resembles that Celestial Throne:
A symbol of each simple heart
That grasps in hope the better part:
Whose life each holy deed combines,
And in the light of virtue shines.
Like fire, though pale in outward show,
Chalcedony at length shall glow;
Carried abroad, its radiance streams:
At home, in shade it hides its gleams:
It marks their holiness and grace
Who do good deeds in secret place.
The Emerald burns, intensely bright,
With radiance of an olive light:
This is the faith that highest shines,
No deed of charity declines,
And seeks no rest, and shuns no strife,
In working out a holy life.
Sardonyx, with its threefold hue,
Sets forth the inner man to view;
Where dark humility is seen,
And chastity with snow-white sheen,
And scarlet marks his joy to bleed
In Martyrdom, if faith shall need.
The Sardius, with its purple red
Sets forth their merits who have bled:
The Martyr band, now blest above,
That agonised for Jesu's Love:
The sixth foundation, not in vain,
The Cross's Mystery to explain.
The golden coloured Chrysolite
Flashes forth sparkles on the night:
Its mystic hues the life reflect
Of men with perfect wisdom decked,
Who shine, in this dark world, like gold,
Through that Blest Spirit Sevenfold.
The sunshine on the sea displays
The watery Beryl's fainter rays:
Of those in this world's wisdom wise
The thoughts and hopes it signifies:
Who long to live more fully blest
With mystic peace of endless rest.
Beyond all gems the Topaz rare
Hath value therefore past compare;
It shines, albeit of colour grey,
Clear as a fair ethereal ray:
And notes the part of them that live
The solid life contemplative.
Some Council, decked in purple state
The Chrysoprase doth imitate:
In the fair tint its face that decks
'Tis intertinged with golden specks:
This is the perfect love, that knows
Kindest return to sternest foes.
The azure Jacinth comes between
The brighter and the dimmer sheen:
The ardour of whose varied ray
Is changed with every changing day:
The Angelic Life it brings to view
Attempered with discretion due.
Last in the Holy City set
With hue of glorious violet,
Forth from the Amethyst are rolled
Sparks crimson-bright, and flames of gold:
The humble heart it signifies
That with its dying Master dies.
These stones, arrayed in goodly row
Set forth the deeds of men below:
The various tints that there have place
The multiplicity of grace.
Who in himself such grace displays
May shine with these in endless rays.
Jerusalem, dear peaceful land!
These for thy twelve foundations stand;
Blessed and nigh to God is he
Who shall be counted worthy thee!
That guardian slumbereth not, nor sleeps,
Who in his charge thy turrets keeps.
King of the Heavenly City blest!
Grant that Thy servants may have rest,
This changeful life for ever past,
And consort with Thy Saints at last;
That we, with all the choir above,
May sing Thy power and praise Thy Love!