Gemstone

A gemstone (also called a gem, fine gem, jewel, precious stone, or semi-precious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments.

I come from the elfin king’s demesne
  With chrysolite, hyacinth, tourmaline;
I have emeralds here of living green;
  I have rubies, each like a cup of wine;
And diamonds, diamonds that never have been
  Outshone by eyes the most divine!
- John Davidson, "The Merchantmen", The Last Ballad, &c. (1899), p. 161

About thy neck a carcanet is bound,
Made of the ruby, pearl and diämond:
A golden ring that shines upon thy thumb:
About thy wrist, the rich dardanium.
Between thy breasts (than down of swans more white)
There plays the sapphire with the chrysolite.
No part besides must of thyself be known,
But by the topaz, opal, chalcedon.
- Robert Herrick, "To Julia" in Hesperides (1648)

When your spirit no longer shines,
you crave gems.
- Linda Hogan, A History of Kindness (2020)

An emerald is as green as grass;
  A ruby red as blood;
A sapphire shines as blue as heaven;
  A flint lies in the mud.
A diamond is a brilliant stone,
  To catch the world’s desire;
An opal holds a fiery spark;
  But a flint holds fire.
- Christina Rossetti, "Jewels" in Sing-Song (1893)

Inestimable stones, unvalued jewels,
All scattered in the bottom of the sea.
Some lay in dead men’s skulls, and in the holes
Where eyes did once inhabit there were crept—
As ’twere in scorn of eyes—reflecting gems,
That wooed the slimy bottom of the deep,
And mocked the dead bones that lay scattered by.
- William Shakespeare, Richard III, I, iv (Clarence)

My daughter! O my ducats! O my daughter!
Fled with a Christian! O my Christian ducats!
Justice! the law! my ducats and my daughter!
A sealèd bag, two sealèd bags of ducats,
Of double ducats, stol’n from me by my daughter!
And jewels, two stones, two rich and precious stones,
Stol’n by my daughter! Justice! find the girl,
She hath the stones upon her and the ducats.
- William Shakespeare, The Merchant of Venice, II, viii (Solanio, quoting Shylock)

Why there, there, there, there! A diamond gone cost me two thousand ducats in Frankfort! The curse never fell upon our nation till now, I never felt it till now. Two thousand ducats in that, and other precious, precious jewels. I would my daughter were dead at my foot, and the jewels in her ear; would she were hearsed at my foot, and the ducats in her coffin.
- William Shakespeare, The Merchant of Venice, III, i (Shylock)

Any life form in any realm – mineral, vegetable, animal, or human – can be said to undergo “enlightenment.” It is, however, an extremely rare occurrence since it is more than an evolutionary progression: It also implies a discontinuity in its development, a leap to an entirely different level of Being and, most important, a lessening of materiality. What could be heavier and more impenetrable than a rock, the densest of all forms? And yet some rocks undergo a change in their molecular structure, turn into crystals, and so become transparent to the light. Some carbons, under inconceivable heat and pressure, turn into diamonds, and some heavy minerals into other precious stones.... Since time immemorial, flowers, crystals, precious stones, and birds have held special significance for the human spirit. Like all lifeforms, they are, of course, temporary manifestations of the underlying one Life, one Consciousness. Their special significance and the reason why humans feel such fascination for and affinity with them can be attributed to their ethereal quality.
- Eckhart Tolle, A New Earth: Awakening to Your Life’s Purpose, (2005) p. 7

“The emerald is a natural emerald, which makes it slightly more valuable than an artificial one.”
“How do you know?” I asked. She’d made the judgment a split second after she’d put the ring into the laser scanner.
“Natural gems have flaws,” the jeweler said. “Artificial gems are perfect.”
- Walter Jon Williams, Send Them Flowers (2007) in Gardner Dozois & Jonathan Strahan (eds.) The New Space Opera (mass market paperback edition, ISBN 978-0-06-135041-2), p. 533

Bible

The Bible on Wikisource

Son of man, take up a lamentation upon the king of Tyrus, and say unto him, Thus saith the Lord GOD; Thou sealest up the sum, full of wisdom, and perfect in beauty. Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.
- Book of Ezekiel 28:12-19 (KJV)

A gift is as a precious stone in the eyes of him that hath it.
- Book of Proverbs 17:8 (KJV)

You have stolen my heart, my sister, my bride; you have stolen my heart with one glance of your eyes, with one jewel of your necklace.
- Song of Solomon 4:9-16 (NIV)

How beautiful your sandaled feet, O prince’s daughter! Your graceful legs are like jewels, the work of an artist’s hands,
- Song of Solomon 7:1-7 (NIV)

Metaphorical usage

Don't waste the Earth — It is our Jewel!
- Buzz Aldrin, 2012, quote from interview video at 1:28, "VAUDE – Opel Project Earth – Buzz Aldrin Interview"

I look upon you as a gem of the old rock.
- Thomas Browne, Hydriotaphia, Urn Burial (1658), Dedication.

All the breath and the bloom of the year in the bag of one bee:
All the wonder and wealth of the mine in the heart of one gem:
In the core of one pearl all the shade and the shine of the sea:
Breath and bloom, shade and shine, — wonder, wealth, and — how far above them —
  Truth, that's brighter than gem,
  Trust, that's purer than pearl, —
  Brightest truth, purest trust in the universe, — all were for me
  In the kiss of one girl.
- Robert Browning, Summum Bonum (1889).

If solid happiness we prize,
Within our breast this jewel lies.
- Nathaniel Cotton, The Fireside, stanza 3, reported in Bartlett's Familiar Quotations, 10th ed. (1919).

How many a thing which we cast to the ground,
When others pick it up, becomes a gem!
- George Meredith, Modern Love (1862) St. 41.

God can find a soul of beauty
Where it falls, as gems of worth
Are found by miners dark in earth.
- Joaquin Miller, Shadows of Shasta (1881), Epigraph, Ch. 4: The Old Gold-Hunter

Dear, I took these trackless masses
Fresh from Him who fashioned them;
Wrought in rock, and hewed fair passes,
Flower set, as sets a gem.
- Joaquin Miller, ' In Classic Shades, and Other Poems (1890), "Juanita".

Self-respect without the respect of others is like a jewel which will not stand the daylight.
- Alfred Nobel, as quoted in A Nobel Affair: The Correspondence between Alfred Nobel and Sofie Hess, p. 48, Translated by Erika Rummel, University of Toronto Press, 2017.

The earth, he'd say, is just a big machine. A big processing plant. A factory. That's your big answer. The big truth. Think of a rock polisher, one of those drums, goes round and round, rolls twenty-four/seven, full of water and rocks and gravel. Grinding it all up. Round and round. Polishing those ugly rocks into gemstones.
- Chuck Palahniuk, Haunted (2005) by, Chapter 6.

Our world hangs like a magnificent jewel in the vastness of space. Every one of us is a part of that jewel. A facet of that jewel. And in the perspective of infinity, our differences are infinitesimal.
- Fred Rogers, Commencement Address at Dartmouth College June 9th, 2002

Sweet are the uses of adversity;
Which, like the toad, ugly and venomous,
Wears yet a precious jewel in his head.
- Duke Senior, in As You Like It (c.1599-1600) written by William Shakespeare, Act II, scene I, line 12.